“Murderous Maths” has been given a gorgeous new cover look. For readers scared of squares and perplexed by primes, the next in the unchallenged “Murderous Maths” series, “Numbers: The Key to the Universe”, reveals how you could win a million dollars and become famous forever (twice). Meanwhile, they must pit their wits against evil Professor Fiendish’s Number Chainand things get ugly when the gangsters meet the unlucky number 13. Using a host of hilarious characters, Kjartan Poskitt presents all the tricks, tips and shortcuts to maths they don’t teach at school.