Hi r2fro,

I think you can use the VLOOKUP formula.

If your X's and Y's are in the range $X$1:$Y$50, then use this formula in C1

=IF(ISNA(VLOOKUP(A1,$X$1:$Y$50,2,0)),"",B1-VLOOKUP(A1,$X$1:$Y$50,2,0))

Let me know if this doesn't work...

Later,
Dennis

re-post: Sorry Pete, I seem to be always posting slower than you...