Change Formula Recalculation Iteration. Change formula recalculation iteration or precision in Excel for Mac. A1 will immediately show 19 and A2 will show 20.

Go to File Options. In the Calculation options section select the Enable iterative calculation check box. Options check the Iteration box and press OK.
Select Formulas Evaluate Formula.
Click Formula and tick the checkbox enable iterative calculations and click OK. In column A next to your original formula enter either TRUE to enable automatic recalculation or FALSE to disable it. Options check the Iteration box and press OK. A1 will immediately show 19 and A2 will show 20.