The central characters are Numberjacks 3, 4, 5 and 6.
- 3 is a bit young to go out on missions, but keen to - full of confidence, energy and noise.
- 4 has more self doubts but keeps plugging away.
- 5 is quite cool and assured and a graceful jumper.
- 6 is very self confident and a great jumper.
The problems are sometimes caused by the younger Numberjacks 0, 1 and 2 escaping from the sofa and inadvertently making things go wrong. More often though, the source of trouble is one of the five Meanies; the Problem Blob, the Shape Japer, Spooky Spoon, the Puzzler and the Number Taker.
- The Problem Blob is a great lump whose blobs of slime make things go wrong.
- The Shape Japer delights in changing the shape of things, doesn't talk much, but laughs a lot.
- Spooky Spoon loves stirring things up and mixing things.
- The Puzzler is a third rate DJ who loves to set weird puzzles for the Numberjacks to solve.
- The Numbertaker is a silent grabber of numbers and uses his various attachments like the number grabber and the number sucker-upper. The Baddies tend to be the cause of different sorts of problems! Trivia:sparkle the pup from bark along with cat has the same voice as the shape japer