Hi,
A simple macro will do this for you.
The following would be the simplest.

Sub Increment()
Range("A1").Value = Range("A1").Value + 1
End Sub

Assign a button or a short-cut key to the macro. Each time it runs, your
number will increase by 1.
I've assumed your number is in cell A1. Change the reference as necessary.

Regards - Dave.