How Many Shuffles Do You Really Need to Randomize Your Deck?

In 1992, mathematicians Dave Bayer and Persi Diaconis proved that seven riffle shuffles are enough to shuffle a deck of cards — but only if you can cut your deck with precision. Decades later, a new proof has finally extended the finding to less precise cuts. On this episode of The Quanta Podcast, host Samir Patel speaks with math editor Jordana Cepelewicz about how a mathematical cutoff phenomenon still exists for riffle shuffling — randomness seems to happen all at once. This topic was covered in a recent story for Quanta Magazine. Each week on The Quanta Podcast, Quanta Magazine editor in chief Samir Patel and Senior Editor Hannah Waters speak with the people behind the award-winning publication to navigate through some of the most important and mind-expanding questions in science and math. In “The Best (and Worst) Ways to Shuffle Cards” from the YouTube channel Numberphile, Persi Diaconis demonstrates different kinds of shuffles, why you might want to stick with a classic riffle shuffle instead of what is called the overhand method and explains his seven shuffles result: https://youtu.be/AxJubaijQbI?si=WctYYRtCZVupMldO