Visual Basic .net Simple Standard Calculator

Step 1: Create New Project with Visual Studio (I am using 2008)
Step 2: Select Windows on Project Types
Step 3: Select Windows Forms Application as Templates
Step 4: Design your simple calculator

Note: The display used is a Label and it has two labels the lower and the upper part namely

        Upper Part:  Secondary Display

        Lower Part: Primary Display

Step 5: Double click on your form and add this codes

Step 6: Add codes to each buttons afterwards

MC

memory = 0

MemoryIndicator.Visible = False

MR

PrimaryDisplay.Text = memory

MemoryIndicator.Visible = True

MS

memory = PrimaryDisplay.Text

MemoryIndicator.Visible = True

M+

memory += CDbl(PrimaryDisplay.Text)

MemoryIndicator.Visible = True

M-

memory -= CDbl(PrimaryDisplay.Text)

MemoryIndicator.Visible = True

<-- (Backspace)

If Len(PrimaryDisplay.Text) > 0 Then

       PrimaryDisplay.Text = Mid(PrimaryDisplay.Text, 1, Len(PrimaryDisplay.Text) - 1)

End If

CE (Clear Equation)

n2 = Nothing

ans = Nothing

operator_active = Nothing

selected_operator = Nothing

SecondaryDisplay.Text = ""

C (Clear)

n1 = Nothing

n2 = Nothing

ans = Nothing

operator_active = Nothing

selected_operator = Nothing

PrimaryDisplay.Text = ""

SecondaryDisplay.Text = ""

+- (Negative Positive)

If Mid(PrimaryDisplay.Text, 1, 1) = "-" Then

            PrimaryDisplay.Text = Mid(PrimaryDisplay.Text, 2, Len(PrimaryDisplay.Text))

Else

            PrimaryDisplay.Text = "-" & PrimaryDisplay.Text

End If

SQRT (Square root)

SecondaryDisplay.Text = "Sqrt(" & PrimaryDisplay.Text & ")"

PrimaryDisplay.Text = CDbl(PrimaryDisplay.Text) ^ 0.5

% (Percentage)

percentage_active = True

SecondaryDisplay.Text = "Percentage(" & selected_operator & ")"

1/x (Reciprocal)

PrimaryDisplay.Text = 1 / CDbl(PrimaryDisplay.Text)

SecondaryDisplay.Text = "(Reciprocal)"

/ (Division)

n1 = CDbl(PrimaryDisplay.Text)

operator_active = True

selected_operator = "/"

SecondaryDisplay.Text = PrimaryDisplay.Text & "/"

* (Multiplication)

n1 = CDbl(PrimaryDisplay.Text)

operator_active = True

selected_operator = "*"

SecondaryDisplay.Text = PrimaryDisplay.Text & "*"

- (Subtraction)

n1 = CDbl(PrimaryDisplay.Text)

operator_active = True

selected_operator = "-"

SecondaryDisplay.Text = PrimaryDisplay.Text & "-"

+ (Addition)

n1 = CDbl(PrimaryDisplay.Text)

operator_active = True

selected_operator = "+"

SecondaryDisplay.Text = PrimaryDisplay.Text & "+"

= (Equal)

n2 = CDbl(PrimaryDisplay.Text)
SecondaryDisplay.Text = SecondaryDisplay.Text & PrimaryDisplay.Text
Select Case selected_operator
       Case "+"
                If percentage_active = False Then
                    ans = n1 + n2
                Else
                    ans = n1 + ((n2 / 100) * n1)
                End If
       Case "-"
                If percentage_active = False Then
                    ans = n1 - n2
                Else
                    ans = n1 - ((n2 / 100) * n1)
                End If
       Case "*"
                If percentage_active = False Then
                    ans = n1 * n2
                Else
                    ans = n1 * ((n2 / 100) * n1)
                End If
       Case "/"
                If percentage_active = False Then
                    ans = n1 / n2
                Else
                    ans = n1 / ((n2 / 100) * n1)
                End If
End Select
PrimaryDisplay.Text = ans
percentage_active = False

Decemal Point

If PrimaryDisplay.Text.Contains(".") = False Then
         PrimaryDisplay.Text = PrimaryDisplay.Text & "."
End If

Number 0 to 9

If operator_active = False Then
            PrimaryDisplay.Text = PrimaryDisplay.Text & "0"
Else
            PrimaryDisplay.Text = "0"
            operator_active = False
End If

Note: Add this codes from number 0 up to number 9 just change the number for each button