Thanks Kevin these work when combined with conditional formatting less than 1.

Don't fully understand the if error function and I don't understand the difference between the 2 examples you show. The second has additional stuff.

I had to edit the formula with the '$'

=IF(ISERROR(SUM(($A3+$K$2)/($B3-2))),"",SUM(($A3+$K$2)/($B3-2)))

Need to get a book on this especially the use of macros. Have used them in Word