At first, I wanted to get myself some knowledge about VBA because it's used often at the company I recently started working. So I decided to do a tutorial about it. I have some knowledge about vb.net from when I went to school.
I do know this is very basic and there is a built-in 'SUM function' in Excel.
While I'm trying to select the 2 cells with the numbers in does this error appear when I select the 2nd cell:
(English version error message from the internet)
The code I typed for the function:
Function fnSum(Num1 As Double, Optional num2 As Variant)
If IsMissing(num2) Then
fnSum = Num1 * Num1
fnSum = Num1 * num2