Help on automatically ending a calculation
 

I have a spread sheet that I use as a financial plan
template. In it, a beginning and ending year are inputed
into one sheet and referenced to another sheet where a
future value calculation is done. How can I cause the
calculation to stop at the ending year value? E.g. if I
input 30 as the start year and ask that it stop at age 60
and go no further than that.

The reason is that I will want to create a graph from
that data. I hope that's not too confusing and the
question is phrased clearly.

Thanks for whatever help you can give.
Jim