In our hyper-modern world we are bombarded with more facts, stats and information than ever before. Often these statistics can seem contradictory and say wildly different things depending on who is sharing them. So in a world where information is so slippery, what can we grasp hold of to make sense of it all? Professor of Information Theory Oliver Johnsons reveals how mathematical thinking can help us understand the myriad data all around us - from the exponentialgrowth of Coronavirus to the rise of social media filter bubbles, from share price fluncutations to the way that rumour spreads, from the datafication of our sports pages to the environmental concerns affecting our planet. Journeying through three sections - Randomness, Statistics and Information - we meet a host of brilliant minds including Alan Turing and Claude Shannon who have shaped the theories underpinning our understanding, and we are equipped with handy tools including the law of large numbers, the critical limit theorem and entropy. Lucid, surprising and entertaining, Numbercrunch supplies the reader with a definitive mathematician's toolkit to make sense of our surroundings, cut through disinformation, and truly understand how our world is changing.