How many jellybeans in cubic foot?

Answer 1

This will depend on the shape of your given volume. A spherical cubic foot would probably contain more than a simple cube. Because of a feature called packing density.

But you could approximate this by filling a small container, whose volume you know, and counting the number. From there it is simple arithmetic, but you should add a few to allow for the diminished packing density of your trial container.

You could also try with several different shaped trial containers.