something similar to
=IF(ISBLANK(A1),"",A1-A2)

is probably what you're looking for.
--
Best Regards,

Luke M
*Remember to click "yes" if this post helped you!*


"Tim Turner" wrote:

i have a spreadsheet to compare inputed predicted and actual values (football
scores that are predicted against actual results) and return a score. Excel
appears to treat an empty cell as a zero value, how can an empty cell be
flagged as "empty" and prevent the calclation taking place untill a value is
entered.

Any help gratefully accepted