A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
This can only happen if values in C20, C30 and C40 are not numbers.
Do following -
- Copy and paste the formulas in Notepad
- Delete the existing formulas in these cells by pressing Delete button
- Right click on these cells > Format Cells > General
- Copy back the formulas
Now, you should get the right result.