Three young, promising students of the math-centric city of Computropolis use mathematics to stop the evil Null Void who has stolen the Divmulti Ray, a laser gun that can multiply or divide anything the ray touches.
The Solvers accidentally drink a shrinking potion, and need to learn all about fractions and decimals in order to mix an antidote to stop the evil Null Void from taking over the city in their absence.