# Decimal Data Type (Visual Basic)

Holds signed 128-bit (16-byte) values representing 96-bit (12-byte) integer numbers scaled by a variable power of 10. The scaling factor specifies the number of digits to the right of the decimal point; it ranges from 0 through 28. With a scale of 0 (no decimal places), the largest possible value is +/-79,228,162,514,264,337,593,543,950,335 (+/-7.9228162514264337593543950335E+28). With 28 decimal places, the largest value is +/-7.9228162514264337593543950335, and the smallest nonzero value is +/-0.0000000000000000000000000001 (+/-1E-28).

## Remarks

The `Decimal`

data type provides the greatest number of significant digits for a number. It supports up to 29 significant digits and can represent values in excess of 7.9228 x 10^28. It is particularly suitable for calculations, such as financial, that require a large number of digits but cannot tolerate rounding errors.

The default value of `Decimal`

is 0.

## Programming Tips

**Precision.**`Decimal`

is not a floating-point data type. The`Decimal`

structure holds a binary integer value, together with a sign bit and an integer scaling factor that specifies what portion of the value is a decimal fraction. Because of this,`Decimal`

numbers have a more precise representation in memory than floating-point types (`Single`

and`Double`

).**Performance.**The`Decimal`

data type is the slowest of all the numeric types. You should weigh the importance of precision against performance before choosing a data type.**Widening.**The`Decimal`

data type widens to`Single`

or`Double`

. This means you can convert`Decimal`

to either of these types without encountering a System.OverflowException error.**Trailing Zeros.**Visual Basic does not store trailing zeros in a`Decimal`

literal. However, a`Decimal`

variable preserves any trailing zeros acquired computationally. The following example illustrates this.`Dim d1, d2, d3, d4 As Decimal d1 = 2.375D d2 = 1.625D d3 = d1 + d2 d4 = 4.000D MsgBox("d1 = " & CStr(d1) & ", d2 = " & CStr(d2) & ", d3 = " & CStr(d3) & ", d4 = " & CStr(d4))`

The output of

`MsgBox`

in the preceding example is as follows:d1 = 2.375, d2 = 1.625, d3 = 4.000, d4 = 4

**Type Characters.**Appending the literal type character`D`

to a literal forces it to the`Decimal`

data type. Appending the identifier type character`@`

to any identifier forces it to`Decimal`

.**Framework Type.**The corresponding type in the .NET Framework is the System.Decimal structure.

## Range

You might need to use the `D`

type character to assign a large value to a `Decimal`

variable or constant. This requirement is because the compiler interprets a literal as `Long`

unless a literal type character follows the literal, as the following example shows.

```
Dim bigDec1 As Decimal = 9223372036854775807 ' No overflow.
Dim bigDec2 As Decimal = 9223372036854775808 ' Overflow.
Dim bigDec3 As Decimal = 9223372036854775808D ' No overflow.
```

The declaration for `bigDec1`

doesn't produce an overflow because the value that's assigned to it falls within the range for `Long`

. The `Long`

value can be assigned to the `Decimal`

variable.

The declaration for `bigDec2`

generates an overflow error because the value that's assigned to it is too large for `Long`

. Because the numeric literal can't first be interpreted as a `Long`

, it can't be assigned to the `Decimal`

variable.

For `bigDec3`

, the literal type character `D`

solves the problem by forcing the compiler to interpret the literal as a `Decimal`

instead of as a `Long`

.

## See Also

System.Decimal

Decimal.Decimal

Math.Round

Data Types

Single Data Type

Double Data Type

Type Conversion Functions

Conversion Summary

Efficient Use of Data Types