What makes a bridge wobble when it's not meant to? How do billions of dollars mysteriously vanish into thin air? How does a building rock when its resonant frequency matches a gym class leaping to Snap's 1990 hit "I've Got The Power"? The answer is maths. Or, to be precise, what happens when maths goes wrong in the real world. The first ever Maths book to be a No.1 bestseller.