Dim First As Double

Dim Second As Double

Dim Sum As Double

Private Sub cmdClear_Click()

txtFirstNumber = " "

txtSecondNumber = " "

txtAnswer = " "

End Sub

Private Sub cmdExit_Click()

End

End Sub

'The code to sum

Private Sub cmdSum_Click()

If Not IsNumeric(txtFirstNumber.Text) Then

    MsgBox ("Enter First Number")

    txtAnswer.Text = ""

    txtFirstNumber.Text = ""

    txtFirstNumber.SetFocus

ElseIf Not IsNumeric(txtSecondNumber.Text) Then

    MsgBox ("Enter Second Number")

    txtAnswer.Text = ""

    txtSecondNumber.Text = ""

    txtSecondNumber.SetFocus

Else

    First = CDbl(txtFirstNumber.Text)

    Second = CDbl(txtSecondNumber.Text)

    Sum = First + Second

    txtAnswer.Text = CStr(Sum)

'I call the answer variable sum

End If

End Sub

'Code to subtract

Private Sub cmdSubtract_Click()

If Not IsNumeric(txtFirstNumber.Text) Then

    MsgBox ("Enter First Number")

    txtAnswer.Text = ""

    txtFirstNumber.Text = ""

    txtFirstNumber.SetFocus

ElseIf Not IsNumeric(txtSecondNumber.Text) Then

    MsgBox ("Enter Second Number")

    txtAnswer.Text = ""

    txtSecondNumber.Text = ""

    txtSecondNumber.SetFocus

Else

    First = CDbl(txtFirstNumber.Text)

    Second = CDbl(txtSecondNumber.Text)

    Sum = First - Second

    txtAnswer.Text = CStr(Sum)

End If

End Sub

'The code to divide

Private Sub cmdDivide_Click()

If Not IsNumeric(txtFirstNumber.Text) Then

    MsgBox ("Enter First Number")

    txtAnswer.Text = ""

    txtFirstNumber.Text = ""

    txtFirstNumber.SetFocus

ElseIf Not IsNumeric(txtSecondNumber.Text) Then

    MsgBox ("Enter Second Number")

    txtAnswer.Text = ""

    txtSecondNumber.Text = ""

    txtSecondNumber.SetFocus

ElseIf txtSecondNumber.Text = 0 Then

    MsgBox ("Division by zero is not nice")

    txtAnswer.Text = ""

    txtSecondNumber.Text = ""

    txtSecondNumber.SetFocus

Else

First = CDbl(txtFirstNumber.Text)

    Second = CDbl(txtSecondNumber.Text)

    Sum = First / Second

    txtAnswer.Text = CStr(Sum)

End If

End Sub

'Code to multiply

Private Sub cmdMultiply_Click()

If Not IsNumeric(txtFirstNumber.Text) Then

    MsgBox ("Enter First Number")

    txtAnswer.Text = ""

    txtFirstNumber.Text = ""

    txtFirstNumber.SetFocus

ElseIf Not IsNumeric(txtSecondNumber.Text) Then

    MsgBox ("Enter Second Number")

    txtAnswer.Text = ""

    txtSecondNumber.Text = ""

    txtSecondNumber.SetFocus

Else

    First = CDbl(txtFirstNumber.Text)

    Second = CDbl(txtSecondNumber.Text)

    Sum = First * Second

    txtAnswer.Text = CStr(Sum)

End If

End Sub