A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
If the 2026 value is 0 you want to leave the 2027 value unchanged. That means the 2027 cell may contain a value. Therefore it doesn't contain a formula.
If the 2026 value is not 0, you want to compute the 2027 value based on the 2026 value, regardless of any existing value in the 2027 cell. That would normally require a formula in the 2027 cell but the cell may already contain a value.
The answer is a macro. You select the 2026 cell and invoke the macro. The macro checks the selected value and
- if 0, exits
- if non zero, computes the new value, stores it in the 2027 cell, and exits.