You should just be able to sum them normally. Whether they're generated
by formulas or not makes no difference, as long as they are numbers.
Have you tried something like
=SUM(A1:A100)
If this doesn't work it might be because the "numbers" generated by
your formulas are, in fact, text. If so this can probably be rectified
by altering the formulas, can you give an example of the formulas?