I'm sorry, but this question makes no sense!
Sheets don't perform computations ?? Formulas do !!
And, if you need help creating formulas, you will need to give us some data and row/column headings to work with.

So please - if you wish help on this forum can you rephrase your question and tell us:

What is the situation that you are in
What data do you have for us to work with
What is it exactly that you want to be able to do
What have you already tried

With this information, we may be able to help you - otherwise we will all just have to look on in despair!