Tableau is different from Excel and no concept of "cells"
But you can use field and table calculation to achieve what you want.
This is just a quick example.
Left / Above does not mean same meaning as excel because it will be different if table format becomes different.
Anyways, I think most of easy calculation you want can be done in Tableau.
But if formula becomes complicated, might be better to prepare the data itself outside Tableau.
[Cell (Left Above)]
[Current - (Left Above)]
Table_Calculation_SM_9.2.twbx 35.0 KB