*Maths is the story of the world around us, and the wisdom it gives us can be the difference between life and death*Maths ends at school and has nothing to do with real life - or so the popular misconception goes. In fact, maths is present in most of our actions and our decisions. When we tap our foot to music, choose which seat on the train to pick or absorb a medical result, we are performing complex maths unconsciously. Not only that: understanding how that is can guide us towards making better decisions in all sorts of situations, from the mundane to the life-changing. In this extraordinary book, mathematical biologist Kit Yates teases out the seven hidden mathematical rules that underlie our common experience, making real-life sense of the equations that govern our lives. How can maths prevent innocent people being convicted for crimes they didn't commit? When is alarm fatigue useful or fatal? And do DNA tests already reveal the full truth? As Yates demonstrates through captivating true-life stories, intriguing case studies and impressive expertise, appreciating how prevalent mathematics is in the everyday can help us to recognise some of the rules that govern our lives. Along the way Yates wrestles with huge ethical and societal issues from abortion to anti-vaccination, from climate change to globalisation. Yet he never loses sight of the sensibility and emotional dimension of the human experience, unlike many books about maths. The result is a captivating, entertaining and surprising read that is utterly relatable.