and his book, liber de ludo, contains many of the basic ideas of probability. almost a century later, blaise pascal and pierre de fermat expanded on cardano's thinking, and they came up with a method to actually calculate probabilities. fermat is probably best known for the famous "fermat's last theorem," a simple-to-state problem about a generalization of the pythagorean theorem that took the world of mathematics 350 years to solve. his day job was as a lawyer, but his passion was mathematics and physics. pascal was the son of a tax collector, and to help his father, he invented the first digital calculator. his deep interests were in both philosophy and mathematics. together, fermat and pascal were widely regarded as two of the most powerful mathematical intellects of their time. although they never met, in 1654 they exchanged a series of letters that most academics today agree was the foundation for the modern theory of probability. their correspondence started after a friend, the gambler chevalier de mere, called upon pascal to get help with a nagging probl