Comedy adventure series, aimed at four- and five-year-olds, in which animated numbers solve mathematical problems in the real world, with input from real children. Using a sequence of lights which guides them in different directions, 4 and 6 are practising their jumping. Agents call in - the sides of boxes are disappearing. The mission is taken on by 6, and he finds boxes with wonky sides and boxes changing their shape. Using the right amount of Brain Gain, the Numberjacks put things right.