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Why swapping cards at random is not a fair shuffle: Fisher–Yates and the 27 paths Shuffling three cards by swapping each one with a random card from the whole row looks fair, but it is not. It makes 3 × 3 × 3 = 27 equally likely paths for… Computing4 min read How one extra digit on your bank card catches your typos The last digit of your bank card number isn't part of your account. It's a check digit, computed from the other fifteen by a recipe an IBM engineer patented in… Computing5 min read Why seven shuffles are enough to mix a deck of cards A 52-card deck can be put in about 8 × 10^67 different orders, yet a few quick shuffles leave a lot of the old order behind. In 1992 Dave Bayer and Persi… Maths4 min read