I'm assuming you want this difference plus one to be in another column...

=IF(C1="yes",B1-A1+1,"")

or, if you want the formula to only reference A and B, then use the
condition that produced the "yes" value...

=IF(B1<A1,B1-A1+1,"")

Rick


"Amanda" wrote in message
...
I have 3 columns of information, A, B, C. C is defined by an if statement
if(B<A,"yes", "").
Now I would like to find the difference between A & B, for all the cells
in
the column that received a "yes" and add to one total.

Is this possible?