The Numberblocks are on an adventure exploring Fraction Island. They are curious to learn why there are four islands when their map only shows one. When they meet a new friend, One Whole, they realise that they need to explore all the islands and find more Fraction Friends if they want to solve the mystery! 

Octo-alert! Lots of things in Numberland have been split into halves, thirds and four equal parts. There's only one block naughty enough to cause such mischief - it's Octonaughty. Octoblock catches up with Octonaughty in The Museum of Numbers as he causes havoc with his new invention, the Fractionator. Octonaughty is splitting things into equal parts to try to steal the Golden Infinity, but how can Octoblock save the day when Octonaughty has the power to split him into four equal parts?