Sum Stories: Equations and Their Origins

Can one prove that 1 + 1 = 2? How long is the coastline of Britain? Which US president proved Pythagoras's theorem on right-angled triangles? Who originated the quadratic equation we learned at school? In how many ways can you tile your bathroom? Is there a formula for prime numbers? How often are two winning lottery numbers consecutive? Who was the witch of Agnesi? What is "the most important theorem in mathematics"? Who scratched mathematical equations on a Dublin bridge? What is a "space...