I have a formula i need to run in a spreadsheet i use which looks like this:

=SUM(100/(AA6+1))

However i have encountered a problem. If cell AA6 is empty, i would like the cell to remain empty. At the moment if cell AA6 is empty the number 100 will be displayed from the formula. I've looked into the ISBLANK function but can't figure it out.

Can anyone help me please.

Thanks