JulieD wrote:
Hi Tom

from what i can tell you want to find the last non-zero in a range (B41:P41)
and when you find the value subtract (I5*J5) from it.

If so, this formula should work for you
=LOOKUP(2,1/(-B41:P41<0),B41:P41)-(I5*J5)

[...]

Agree. Just to avoid accidents with text and neg numbers...

=LOOKUP(2,1/((B41:P410)*ISNUMBER(B41:PK1)),B41:P41)-(I5*J5)