# Enumerable.Sum Method

## Definition

Computes the sum of a sequence of numeric values.

## Overloads

Sum(IEnumerable<Nullable<Int32>>) |
Computes the sum of a sequence of nullable Int32 values. |

Sum(IEnumerable<Nullable<Single>>) |
Computes the sum of a sequence of nullable Single values. |

Sum(IEnumerable<Nullable<Int64>>) |
Computes the sum of a sequence of nullable Int64 values. |

Sum(IEnumerable<Single>) |
Computes the sum of a sequence of Single values. |

Sum(IEnumerable<Nullable<Double>>) |
Computes the sum of a sequence of nullable Double values. |

Sum(IEnumerable<Int32>) |
Computes the sum of a sequence of Int32 values. |

Sum(IEnumerable<Int64>) |
Computes the sum of a sequence of Int64 values. |

Sum(IEnumerable<Double>) |
Computes the sum of a sequence of Double values. |

Sum(IEnumerable<Decimal>) |
Computes the sum of a sequence of Decimal values. |

Sum(IEnumerable<Nullable<Decimal>>) |
Computes the sum of a sequence of nullable Decimal values. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>) |
Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>) |
Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>) |
Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>) |
Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>) |
Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>) |
Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int64>) |
Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int32>) |
Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) |
Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence. |

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>) |
Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. |

## Sum(IEnumerable<Nullable<Int32>>)

Computes the sum of a sequence of nullable Int32 values.

```
public:
[System::Runtime::CompilerServices::Extension]
static Nullable<int> Sum(System::Collections::Generic::IEnumerable<Nullable<int>> ^ source);
```

`public static int? Sum (this System.Collections.Generic.IEnumerable<Nullable<int>> source);`

`static member Sum : seq<Nullable<int>> -> Nullable<int>`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Integer))) As Nullable(Of Integer)
```

#### Parameters

- source
- IEnumerable<Nullable<Int32>>

A sequence of nullable Int32 values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

The sum is larger than MaxValue.

### Examples

The following code example demonstrates how to use Sum(IEnumerable<Nullable<Single>>) to sum the values of a sequence.

Note

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, substitute the elements of the source sequence with elements of the appropriate numerical type.

```
float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };
float? sum = points.Sum();
Console.WriteLine("Total points earned: {0}", sum);
/*
This code produces the following output:
Total points earned: 311.39
*/
```

```
' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) =
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}
' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()
' Display the output.
Console.WriteLine($"Total points earned: {sum}")
' This code produces the following output:
'
' Total points earned: 311.39
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

In Visual Basic query expression syntax, an `Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Nullable<Single>>)

Computes the sum of a sequence of nullable Single values.

```
public:
[System::Runtime::CompilerServices::Extension]
static Nullable<float> Sum(System::Collections::Generic::IEnumerable<Nullable<float>> ^ source);
```

`public static float? Sum (this System.Collections.Generic.IEnumerable<Nullable<float>> source);`

`static member Sum : seq<Nullable<single>> -> Nullable<single>`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Single))) As Nullable(Of Single)
```

#### Parameters

- source
- IEnumerable<Nullable<Single>>

A sequence of nullable Single values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

### Examples

The following code example demonstrates how to use Sum(IEnumerable<Nullable<Single>>) to sum the values of a sequence.

```
float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };
float? sum = points.Sum();
Console.WriteLine("Total points earned: {0}", sum);
/*
This code produces the following output:
Total points earned: 311.39
*/
```

```
' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) =
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}
' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()
' Display the output.
Console.WriteLine($"Total points earned: {sum}")
' This code produces the following output:
'
' Total points earned: 311.39
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

In Visual Basic query expression syntax, an `Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Nullable<Int64>>)

Computes the sum of a sequence of nullable Int64 values.

```
public:
[System::Runtime::CompilerServices::Extension]
static Nullable<long> Sum(System::Collections::Generic::IEnumerable<Nullable<long>> ^ source);
```

`public static long? Sum (this System.Collections.Generic.IEnumerable<Nullable<long>> source);`

`static member Sum : seq<Nullable<int64>> -> Nullable<int64>`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Long))) As Nullable(Of Long)
```

#### Parameters

- source
- IEnumerable<Nullable<Int64>>

A sequence of nullable Int64 values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

The sum is larger than MaxValue.

### Examples

The following code example demonstrates how to use Sum(IEnumerable<Nullable<Single>>) to sum the values of a sequence.

Note

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, substitute the elements of the source sequence with elements of the appropriate numerical type.

```
float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };
float? sum = points.Sum();
Console.WriteLine("Total points earned: {0}", sum);
/*
This code produces the following output:
Total points earned: 311.39
*/
```

```
' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) =
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}
' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()
' Display the output.
Console.WriteLine($"Total points earned: {sum}")
' This code produces the following output:
'
' Total points earned: 311.39
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

In Visual Basic query expression syntax, an `Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Single>)

Computes the sum of a sequence of Single values.

```
public:
[System::Runtime::CompilerServices::Extension]
static float Sum(System::Collections::Generic::IEnumerable<float> ^ source);
```

`public static float Sum (this System.Collections.Generic.IEnumerable<float> source);`

`static member Sum : seq<single> -> single`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Single)) As Single
```

#### Parameters

- source
- IEnumerable<Single>

A sequence of Single values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

### Examples

The following code example demonstrates how to use Sum(IEnumerable<Single>) to sum the values of a sequence.

```
List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };
float sum = numbers.Sum();
Console.WriteLine("The sum of the numbers is {0}.", sum);
/*
This code produces the following output:
The sum of the numbers is 635.13.
*/
```

```
' Create a list of Single values.
Dim numbers As New List(Of Single)(New Single() _
{43.68F, 1.25F, 583.7F, 6.5F})
' Get the sum of values in the list.
Dim sum As Single = numbers.Sum()
' Display the output.
Console.WriteLine($"The sum of the numbers is {sum}")
' This code produces the following output:
'
' The sum of the numbers is 635.13
```

### Remarks

This method returns zero if `source`

contains no elements.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Nullable<Double>>)

Computes the sum of a sequence of nullable Double values.

```
public:
[System::Runtime::CompilerServices::Extension]
static Nullable<double> Sum(System::Collections::Generic::IEnumerable<Nullable<double>> ^ source);
```

`public static double? Sum (this System.Collections.Generic.IEnumerable<Nullable<double>> source);`

`static member Sum : seq<Nullable<double>> -> Nullable<double>`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Double))) As Nullable(Of Double)
```

#### Parameters

- source
- IEnumerable<Nullable<Double>>

A sequence of nullable Double values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

### Examples

Note

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, substitute the elements of the source sequence with elements of the appropriate numerical type.

```
float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };
float? sum = points.Sum();
Console.WriteLine("Total points earned: {0}", sum);
/*
This code produces the following output:
Total points earned: 311.39
*/
```

```
' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) =
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}
' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()
' Display the output.
Console.WriteLine($"Total points earned: {sum}")
' This code produces the following output:
'
' Total points earned: 311.39
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Int32>)

Computes the sum of a sequence of Int32 values.

```
public:
[System::Runtime::CompilerServices::Extension]
static int Sum(System::Collections::Generic::IEnumerable<int> ^ source);
```

`public static int Sum (this System.Collections.Generic.IEnumerable<int> source);`

`static member Sum : seq<int> -> int`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Integer)) As Integer
```

#### Parameters

- source
- IEnumerable<Int32>

A sequence of Int32 values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

The sum is larger than MaxValue.

### Examples

The following code example demonstrates how to use Sum(IEnumerable<Single>) to sum the values of a sequence.

Note

```
List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };
float sum = numbers.Sum();
Console.WriteLine("The sum of the numbers is {0}.", sum);
/*
This code produces the following output:
The sum of the numbers is 635.13.
*/
```

```
' Create a list of Single values.
Dim numbers As New List(Of Single)(New Single() _
{43.68F, 1.25F, 583.7F, 6.5F})
' Get the sum of values in the list.
Dim sum As Single = numbers.Sum()
' Display the output.
Console.WriteLine($"The sum of the numbers is {sum}")
' This code produces the following output:
'
' The sum of the numbers is 635.13
```

### Remarks

This method returns zero if `source`

contains no elements.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Int64>)

Computes the sum of a sequence of Int64 values.

```
public:
[System::Runtime::CompilerServices::Extension]
static long Sum(System::Collections::Generic::IEnumerable<long> ^ source);
```

`public static long Sum (this System.Collections.Generic.IEnumerable<long> source);`

`static member Sum : seq<int64> -> int64`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Long)) As Long
```

#### Parameters

- source
- IEnumerable<Int64>

A sequence of Int64 values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

The sum is larger than MaxValue.

### Examples

The following code example demonstrates how to use Sum(IEnumerable<Single>) to sum the values of a sequence.

Note

```
List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };
float sum = numbers.Sum();
Console.WriteLine("The sum of the numbers is {0}.", sum);
/*
This code produces the following output:
The sum of the numbers is 635.13.
*/
```

```
' Create a list of Single values.
Dim numbers As New List(Of Single)(New Single() _
{43.68F, 1.25F, 583.7F, 6.5F})
' Get the sum of values in the list.
Dim sum As Single = numbers.Sum()
' Display the output.
Console.WriteLine($"The sum of the numbers is {sum}")
' This code produces the following output:
'
' The sum of the numbers is 635.13
```

### Remarks

This method returns zero if `source`

contains no elements.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Double>)

Computes the sum of a sequence of Double values.

```
public:
[System::Runtime::CompilerServices::Extension]
static double Sum(System::Collections::Generic::IEnumerable<double> ^ source);
```

`public static double Sum (this System.Collections.Generic.IEnumerable<double> source);`

`static member Sum : seq<double> -> double`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Double)) As Double
```

#### Parameters

- source
- IEnumerable<Double>

A sequence of Double values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

### Examples

Note

```
List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };
float sum = numbers.Sum();
Console.WriteLine("The sum of the numbers is {0}.", sum);
/*
This code produces the following output:
The sum of the numbers is 635.13.
*/
```

```
' Create a list of Single values.
Dim numbers As New List(Of Single)(New Single() _
{43.68F, 1.25F, 583.7F, 6.5F})
' Get the sum of values in the list.
Dim sum As Single = numbers.Sum()
' Display the output.
Console.WriteLine($"The sum of the numbers is {sum}")
' This code produces the following output:
'
' The sum of the numbers is 635.13
```

### Remarks

This method returns zero if `source`

contains no elements.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Decimal>)

Computes the sum of a sequence of Decimal values.

```
public:
[System::Runtime::CompilerServices::Extension]
static System::Decimal Sum(System::Collections::Generic::IEnumerable<System::Decimal> ^ source);
```

`public static decimal Sum (this System.Collections.Generic.IEnumerable<decimal> source);`

`static member Sum : seq<decimal> -> decimal`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Decimal)) As Decimal
```

#### Parameters

- source
- IEnumerable<Decimal>

A sequence of Decimal values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

The sum is larger than MaxValue.

### Examples

Note

```
List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };
float sum = numbers.Sum();
Console.WriteLine("The sum of the numbers is {0}.", sum);
/*
This code produces the following output:
The sum of the numbers is 635.13.
*/
```

```
' Create a list of Single values.
Dim numbers As New List(Of Single)(New Single() _
{43.68F, 1.25F, 583.7F, 6.5F})
' Get the sum of values in the list.
Dim sum As Single = numbers.Sum()
' Display the output.
Console.WriteLine($"The sum of the numbers is {sum}")
' This code produces the following output:
'
' The sum of the numbers is 635.13
```

### Remarks

The Sum(IEnumerable<Decimal>) method returns zero if `source`

contains no elements.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum(IEnumerable<Nullable<Decimal>>)

Computes the sum of a sequence of nullable Decimal values.

```
public:
[System::Runtime::CompilerServices::Extension]
static Nullable<System::Decimal> Sum(System::Collections::Generic::IEnumerable<Nullable<System::Decimal>> ^ source);
```

`public static decimal? Sum (this System.Collections.Generic.IEnumerable<Nullable<decimal>> source);`

`static member Sum : seq<Nullable<decimal>> -> Nullable<decimal>`

```
<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Decimal))) As Nullable(Of Decimal)
```

#### Parameters

- source
- IEnumerable<Nullable<Decimal>>

A sequence of nullable Decimal values to calculate the sum of.

#### Returns

The sum of the values in the sequence.

#### Exceptions

`source`

is `null`

.

The sum is larger than MaxValue.

### Examples

Note

```
float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };
float? sum = points.Sum();
Console.WriteLine("Total points earned: {0}", sum);
/*
This code produces the following output:
Total points earned: 311.39
*/
```

```
' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) =
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}
' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()
' Display the output.
Console.WriteLine($"Total points earned: {sum}")
' This code produces the following output:
'
' Total points earned: 311.39
```

### Remarks

This method returns zero if `source`

contains no elements.

The result doesnot include values that are `null`

.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>)

Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static float Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, float> ^ selector);
```

`public static float Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,float> selector);`

`static member Sum : seq<'Source> * Func<'Source, single> -> single`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Single)) As Single
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

### Examples

The following code example demonstrates how to use Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) to sum the projected values of a sequence.

Note

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, change the body of the `selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

The Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>) method returns zero if `source`

contains no elements.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically Single.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>)

Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<float> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<float>> ^ selector);
```

`public static float? Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,Nullable<float>> selector);`

`static member Sum : seq<'Source> * Func<'Source, Nullable<single>> -> Nullable<single>`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Single))) As Nullable(Of Single)
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

### Examples

The following code example demonstrates how to use Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) to sum the projected values of a sequence.

Note

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, change the body of the `selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically `Nullable<Single>`

in C# or `Nullable(Of Single)`

in Visual Basic.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>)

Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<long> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<long>> ^ selector);
```

`public static long? Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,Nullable<long>> selector);`

`static member Sum : seq<'Source> * Func<'Source, Nullable<int64>> -> Nullable<int64>`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Long))) As Nullable(Of Long)
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

The sum is larger than MaxValue.

### Examples

The following code example demonstrates how to use Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) to sum the projected values of a sequence.

Note

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, change the body of the `selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically `Nullable<Int64>`

in C# or `Nullable(Of Int64)`

in Visual Basic

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>)

Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<int> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<int>> ^ selector);
```

`public static int? Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,Nullable<int>> selector);`

`static member Sum : seq<'Source> * Func<'Source, Nullable<int>> -> Nullable<int>`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Integer))) As Nullable(Of Integer)
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

The sum is larger than MaxValue.

### Examples

Note

`selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically `Nullable<Int32>`

in C# or `Nullable(Of Int32)`

in Visual Basic.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>)

Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<double> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<double>> ^ selector);
```

`public static double? Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,Nullable<double>> selector);`

`static member Sum : seq<'Source> * Func<'Source, Nullable<double>> -> Nullable<double>`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Double))) As Nullable(Of Double)
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

### Examples

Note

`selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not include values that are `null`

.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically `Nullable<Double>`

in C# or `Nullable(Of Double)`

in Visual Basic.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>)

Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<System::Decimal> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<System::Decimal>> ^ selector);
```

`public static decimal? Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,Nullable<decimal>> selector);`

`static member Sum : seq<'Source> * Func<'Source, Nullable<decimal>> -> Nullable<decimal>`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Decimal))) As Nullable(Of Decimal)
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

The sum is larger than MaxValue.

### Examples

Note

`selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

The result does not included values that are `null`

.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically `Nullable<Decimal>`

in C# or `Nullable(Of Decimal)`

in Visual Basic.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int64>)

Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static long Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, long> ^ selector);
```

`public static long Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,long> selector);`

`static member Sum : seq<'Source> * Func<'Source, int64> -> int64`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Long)) As Long
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

The sum is larger than MaxValue.

### Examples

Note

`selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically Int64.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int32>)

Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static int Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, int> ^ selector);
```

`public static int Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,int> selector);`

`static member Sum : seq<'Source> * Func<'Source, int> -> int`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Integer)) As Integer
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

The sum is larger than MaxValue.

### Examples

Note

`selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically Int32.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>)

Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static double Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, double> ^ selector);
```

`public static double Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,double> selector);`

`static member Sum : seq<'Source> * Func<'Source, double> -> double`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Double)) As Double
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

### Examples

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically Double.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.

### See also

### Applies to

## Sum<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>)

Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static System::Decimal Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, System::Decimal> ^ selector);
```

`public static decimal Sum<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,decimal> selector);`

`static member Sum : seq<'Source> * Func<'Source, decimal> -> decimal`

```
<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Decimal)) As Decimal
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

#### Returns

The sum of the projected values.

#### Exceptions

`source`

or `selector`

is `null`

.

The sum is larger than MaxValue.

### Examples

Note

`selector`

function.

```
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}
public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };
double totalWeight = packages.Sum(pkg => pkg.Weight);
Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}
/*
This code produces the following output:
The total weight of the packages is: 83.7
*/
```

```
Structure Package
Public Company As String
Public Weight As Double
End Structure
Sub SumEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
New Package With {.Company = "Adventure Works", .Weight = 33.8}})
' Sum the values from each item's Weight property.
Dim totalWeight As Double = packages.Sum(Function(pkg) _
pkg.Weight)
' Display the result.
Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub
' This code produces the following output:
'
' The total weight of the packages is: 83.7
```

### Remarks

This method returns zero if `source`

contains no elements.

You can apply this method to a sequence of arbitrary values if you provide a function, `selector`

, that projects the members of `source`

into a numeric type, specifically Decimal.

`Aggregate Into Sum()`

clause translates to an invocation of Sum.