How many beans make five?

How many beans make five?

An old British expression, used in the context "he knows how many beans make five", meaning "he knows his stuff" or referring to one who's good at mathematical puzzlers.

Derives from the days of the abacus, when the wooden beads (beans) were moved along in various increments.

Answer:

Two beans, a bean and a half, a bean and half a bean.