i'm guessing it's a if then. i'm trying to calculate the BMI (body mass
index).
i have 2 "inches" fields and 2 "weight" fields.
i want to calculate whichever is populated into a different formula.

so if
a1=0 b1=4
a2=4 b2=5
but i want to use either a1 or a2 (whichever is populated) and b1 or b2
(whichever is populated).

so (a1*703)/(b1*b1) is what i'm looking for essentially. hopefully this
makes sense.
tia