The Numberjacks are animated characters - the numbers zero to nine - who live in an ordinary sofa and solve problems outside. Each episode has the same structure. At the beginning of the episode, some of the Numberjacks will be engaged in an activity that will have relevance to the problem that is later discovered. Then an "agent" (a live-action child) will call in and describe the problem that is occurring. One or two of the Numberjacks will go out into the real world to solve the problem, while the remaining Numberjacks stay in their base and watch their progress on a screen. As soon as the problem is understood, 5 imagines what else could go wrong if it wasn't solved.
Once outside, the Numberjacks are shown in a live-action setting (although still animated themselves). They diagnose the problem by examination and with help from additional ideas from the agents, who call into the base. Problems are solved by using "Brain Gain", a magical force of power.
Once solved, the Numberjacks return to their base, replay what happened on a screen and then challenge the viewer to think about a related problem.
The problems encountered are all based around simple mathematical concepts and the programme is intended to stimulate young children's interest in mathematics.