Calculate only if cell contains a number

Question

I have a cells in one row with numbers which I need to subtract and sum like this:

=(C2-B2)+(E2-D2)+(G2-F2)+(I2-H2) etc..

Always second cell minus previous in two-cell chunks. And in the end of this row I get result from 30+ calculations.

For now it works without problem, but problem occurs when I introduce non-number data in one of two-cell chunk, which I don't want to be calculated.

Example sheet: [ link ]

Answer 1

You could try to improve your formula by using built-in functions like

• IFERROR
• ISNUMBER together with IF