If I shuffle a deck of 52 cards and hold it out for you to pick one, I can do so with an astonishing guarantee: No other deck in history has ever existed in this exact configuration — and no other deck ever will.
That doesn’t seem right, does it? Playing cards have been around since the 9th century, the standard deck since 1516. A lot of shuffling has happened since then. Cowboys played cards. World War II soldiers played cards. Today, millions of people play poker, black jack, and bridge. How do configurations not repeat?
Well, as I learned from Tim Urban, the number of unique arrangements can be calculated with a simple formula: 52 factorial, or 52! in math terms.
A factorial is simply a multiplication of decreasing factors. 3! is 6. You take 3 * 2 * 1. 5! is 120. You take 5 * 4 * 3 * 2 * 1. Therefore, 52! is just 52 * 51 * 50…and so on. Here is the number this results in:
80658175170943878571660636856403766975289505440883277824000000000000
Yeah. There’s no decimal point in there. Let’s see if we can wrap our brains around this number.
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