One way:

=IF(D9="","",IF(E9="","You must enter a number in E9",""))

(I assume that F9 was a typo.)

In article ,
"KimberlyC" wrote:

Hi

I'm need a formula in cell C9 that does the following:

If D9 is blank then C9 is blank
If D9 is not blank and F9 is blank then I need C9 to display a message "You
must enter a number is E9"
If D9 is not blank and E9 is not blank, then C9 is blank.

Any help is greatly appreciated!!
Thanks in advance
Kimberly