How do you find the equation for the volume of a regular shaped object?

Answer 1

as a rule of thumb... average cross sectional area x average length.

typically for a cube or box shape object; the rule is width x length x height.

finding volumes and areas of more complicated shapes can be found using integral calculus or (anti-differential calculus)

but for simplicity sake, as you specify a "regular shape"; width x length x height should be fine!

hope this helps