Photo credit: By Alan Cleaver (Flickr: Shuffling the deck) [CC BY 2.0], via Wikimedia Commons

In a deck of 52 cards, there are 80,658,175,170,943,878,571,660,636,856,403,766,
975,289,505,440,883,277,824,000,000,000,000 possible combinations. To give you an idea of how many that is, here is how long it would take to go through every possible permutation of cards. If every star in our galaxy had a trillion planets, each with a trillion people living on them, and each of these people has a trillion packs of cards and somehow they manage to make unique shuffles 1,000 times per second, and they’d been doing that since the Big Bang, they’d only just now be starting to repeat shuffles.

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