Attribute VB_Name = "Module1"
Option Explicit
Global Const pi As Double = 3.14159265358979

Sub total(a, c, b)
    Select Case b
        Case 0
            a = a + c
        Case 1
            a = a - c
        Case 2
            a = a * c
        Case 3
            If c = 0 Then MsgBox "0不能做除數", vbCritical: Exit Sub
            a = a / c
    End Select
End Sub