# 7단계: 곱하기 및 나누기 문제 추가Step 7: Add multiplication and division problems

이 자습서의 7단계에서는 곱하기와 나누기 문제를 추가합니다. 하지만 먼저 이렇게 변경하는 방법을 살펴보겠습니다.In the seventh part of this tutorial, you'll add multiplication and division problems, but first think about how to make that change. 값을 저장하는 첫 단계를 알아야 합니다.Consider the initial step, which involves storing values.

## 곱하기 및 나누기 문제를 추가하려면To add multiplication and division problems

1. 정수 변수를 네 개 더 폼에 추가합니다.Add four more integer variables to the form.

``````Public Class Form1

' Create a Random object called randomizer
' to generate random numbers.
Private randomizer As New Random

' These integer variables store the numbers
' for the addition problem.
Private addend1 As Integer
Private addend2 As Integer

' These integer variables store the numbers
' for the subtraction problem.
Private minuend As Integer
Private subtrahend As Integer

' These integer variables store the numbers
' for the multiplication problem.
Private multiplicand As Integer
Private multiplier As Integer

' These integer variables store the numbers
' for the division problem.
Private dividend As Integer
Private divisor As Integer

' This integer variable keeps track of the
' remaining time.
Private timeLeft As Integer
``````
``````public partial class Form1 : Form
{
// Create a Random object called randomizer
// to generate random numbers.
Random randomizer = new Random();

// These integer variables store the numbers
// for the addition problem.
int addend1;
int addend2;

// These integer variables store the numbers
// for the subtraction problem.
int minuend;
int subtrahend;

// These integer variables store the numbers
// for the multiplication problem.
int multiplicand;
int multiplier;

// These integer variables store the numbers
// for the division problem.
int dividend;
int divisor;

// This integer variable keeps track of the
// remaining time.
int timeLeft;
``````
2. 이전과 마찬가지로 `StartTheQuiz()` 메서드를 수정하여 곱하기 및 나누기 문제를 난수로 채웁니다.As you did before, modify the `StartTheQuiz()` method to fill in random numbers for the multiplication and division problems.

``````''' <summary>
''' Start the quiz by filling in all of the problem
''' values and starting the timer.
''' </summary>
''' <remarks></remarks>
Public Sub StartTheQuiz()

' Fill in the addition problem.
' Generate two random numbers to add.
' Store the values in the variables 'addend1' and 'addend2'.
addend1 = randomizer.Next(51)
addend2 = randomizer.Next(51)

' Convert the two randomly generated numbers
' into strings so that they can be displayed
' in the label controls.
plusLeftLabel.Text = addend1.ToString()
plusRightLabel.Text = addend2.ToString()

' 'sum' is the name of the NumericUpDown control.
' This step makes sure its value is zero before
' adding any values to it.
sum.Value = 0

' Fill in the subtraction problem.
minuend = randomizer.Next(1, 101)
subtrahend = randomizer.Next(1, minuend)
minusLeftLabel.Text = minuend.ToString()
minusRightLabel.Text = subtrahend.ToString()
difference.Value = 0

' Fill in the multiplication problem.
multiplicand = randomizer.Next(2, 11)
multiplier = randomizer.Next(2, 11)
timesLeftLabel.Text = multiplicand.ToString()
timesRightLabel.Text = multiplier.ToString()
product.Value = 0

' Fill in the division problem.
divisor = randomizer.Next(2, 11)
Dim temporaryQuotient As Integer = randomizer.Next(2, 11)
dividend = divisor * temporaryQuotient
dividedLeftLabel.Text = dividend.ToString()
dividedRightLabel.Text = divisor.ToString()
quotient.Value = 0

' Start the timer.
timeLeft = 30
timeLabel.Text = "30 seconds"
Timer1.Start()

End Sub
``````
``````/// <summary>
/// Start the quiz by filling in all of the problem
/// values and starting the timer.
/// </summary>
public void StartTheQuiz()
{
// Fill in the addition problem.
// Generate two random numbers to add.
// Store the values in the variables 'addend1' and 'addend2'.
addend1 = randomizer.Next(51);
addend2 = randomizer.Next(51);

// Convert the two randomly generated numbers
// into strings so that they can be displayed
// in the label controls.
plusLeftLabel.Text = addend1.ToString();
plusRightLabel.Text = addend2.ToString();

// 'sum' is the name of the NumericUpDown control.
// This step makes sure its value is zero before
// adding any values to it.
sum.Value = 0;

// Fill in the subtraction problem.
minuend = randomizer.Next(1, 101);
subtrahend = randomizer.Next(1, minuend);
minusLeftLabel.Text = minuend.ToString();
minusRightLabel.Text = subtrahend.ToString();
difference.Value = 0;

// Fill in the multiplication problem.
multiplicand = randomizer.Next(2, 11);
multiplier = randomizer.Next(2, 11);
timesLeftLabel.Text = multiplicand.ToString();
timesRightLabel.Text = multiplier.ToString();
product.Value = 0;

// Fill in the division problem.
divisor = randomizer.Next(2, 11);
int temporaryQuotient = randomizer.Next(2, 11);
dividend = divisor * temporaryQuotient;
dividedLeftLabel.Text = dividend.ToString();
dividedRightLabel.Text = divisor.ToString();
quotient.Value = 0;

// Start the timer.
timeLeft = 30;
timeLabel.Text = "30 seconds";
timer1.Start();
}
``````
3. 곱하기 및 나누기 문제에 대해서도 확인하도록 `CheckTheAnswer()` 메서드를 수정합니다.Modify the `CheckTheAnswer()` method so that it also checks the multiplication and division problems.

``````''' <summary>
''' Check the answers to see if the user got everything right.
''' </summary>
''' <returns>True if the answer's correct, false otherwise.</returns>
''' <remarks></remarks>
Public Function CheckTheAnswer() As Boolean

If addend1 + addend2 = sum.Value AndAlso
minuend - subtrahend = difference.Value AndAlso
multiplicand * multiplier = product.Value AndAlso
dividend / divisor = quotient.Value Then

Return True
Else
Return False
End If

End Function
``````
``````/// <summary>
/// Check the answers to see if the user got everything right.
/// </summary>
/// <returns>True if the answer's correct, false otherwise.</returns>
private bool CheckTheAnswer()
{
if ((addend1 + addend2 == sum.Value)
&& (minuend - subtrahend == difference.Value)
&& (multiplicand * multiplier == product.Value)
&& (dividend / divisor == quotient.Value))
return true;
else
return false;
}
``````

키보드를 사용하여 곱하기 기호(×)와 나누기 기호(÷)를 입력하기가 쉽지 않으므로 Visual C# 및 Visual Basic에서는 별표(*)를 곱하기에, 슬래시(/)를 나누기에 각각 사용합니다.You can't easily enter the multiplication sign (×) and the division sign (÷) using the keyboard, so Visual C# and Visual Basic accept an asterisk (*) for multiplication and a slash mark (/) for division.

4. 시간이 다 되면 자동으로 올바른 답을 채우도록 타이머의 Tick 이벤트 처리기 마지막 부분을 변경합니다.Change the last part of the timer's Tick event handler so that it fills in the correct answer when time runs out.

``````Else
' If the user ran out of time, stop the timer, show
' a MessageBox, and fill in the answers.
Timer1.Stop()
timeLabel.Text = "Time's up!"
MessageBox.Show("You didn't finish in time.", "Sorry!")
sum.Value = addend1 + addend2
difference.Value = minuend - subtrahend
product.Value = multiplicand * multiplier
quotient.Value = dividend / divisor
startButton.Enabled = True
End If
``````
``````else
{
// If the user ran out of time, stop the timer, show
// a MessageBox, and fill in the answers.
timer1.Stop();
timeLabel.Text = "Time's up!";
MessageBox.Show("You didn't finish in time.", "Sorry");
sum.Value = addend1 + addend2;
difference.Value = minuend - subtrahend;
product.Value = multiplicand * multiplier;
quotient.Value = dividend / divisor;
startButton.Enabled = true;
}
``````
5. 프로그램을 저장하고 실행합니다.Save and run your program.

다음 그림과 같이 퀴즈를 푸는 사람은 네 가지 문제에 대한 답을 입력하여 퀴즈를 완료해야 합니다.Quiz takers must answer four problems to complete the quiz, as the following illustration shows.

네 개의 문제가 있는 수학 퀴즈 Math quiz with four problems