=SUM(IF(M6:M20<"",N6:N20/M6:M20))

which is an array formula, it should be committed with Ctrl-Shift-Enter, not
just Enter.

--
HTH

Bob Phillips

(remove nothere from email address if mailing direct)

"oxicottin" wrote in message
...
I have a excel sheet that I want to divide two long rows of cell by each
other. I want to divide n6 through N20 / M6 through M20. In the N row I
have
a percent and I want to divide it by Time in the M row. Please help!!