Change an existing formula in Numbers for iCloud
You can edit an existing formula so that it refers to different cells.
Double-click the results cell containing the formula you want to edit.
The formula editor opens.
Do any of the following:
Add more cell references: Place the insertion point in the formula or within the argument area for the function, then select the new cells you want to add.
Remove cell references: Place the insertion point within the formula or within the argument area for the function, select the unwanted cell references, then press Delete.
Change the cell references: Select the existing cell addresses in the formula or function, then select the new cells.
If you’re editing cell references for a formula that you created using mathematical symbols (as opposed to a predefined function), you may also need to edit the symbols.
Press Return or click the Checkmark button in the formula editor when you’re done.
If you click the Cancel button , you exit the current cell without saving the formula in it.