The Aftermath returns to some of the problems posed early in the book. The questions solved include: In which years does February have four Sundays? How many shuffles are needed to restore the order of the cards in a pack with two Jokers? How do prime numbers keep our credit cards secure? Are there infinitely many primes with final digit 9? Integers, squares and cubes, prime numbers and perfect numbers are revisited, with instructions for solving some of the ancient puzzles that inspired generations of mathematicians, and concluding with some of the unsolved problems in this exciting field of modern mathematics.