Games

# What's The Best Way To Shuffle A Deck Of Cards?

When it comes to a deck of cards, shuffling is shuffling, right? Nope. There are plenty of ways to mix up your deck, but they are not all created equal.

## Shuffle Up And Deal

How do you shuffle your playing cards? The riffle shuffle — separating the deck into two piles and putting them back together as in the photo above — may be the most common way, but if you want to truly mix up the deck, you'll need to do that riffle about seven times. Persi Diaconis, a professional magician turned mathematician, proved this in 1992. Diaconis has examined several modes of shuffling in an effort to weed out the inefficient ones and highlight those that will lead to fair gameplay. Another popular type of shuffle that is surprisingly inefficient? The overhand shuffle (again, check out the picture above). Turns out it would take up to 10,000 overhand shuffles to "randomize" a deck as well as 7 riffle shuffles.

## Smoosh It

A tip for your next poker game: One type of shuffle that's especially hard to study is the "smoosh," or the technique that involves simply laying out all the cards face-down in a mess and swirling them together with your hands. Diaconis found that 1 minute of smooshing typically results in an unpredictable arrangement of cards. So next time you have friends over to play cards, try it. This shuffle may not look as fancy as the riffle or the overhand, but it'll best ensure a fair game.

#### The Best (And Worst) Way To Shuffle Cards

Trust us, quit overhand shuffling.

– Numberphile

### Key Facts In This Video

1. It takes about 10,000 overhand shuffles to mix up a deck of cards so that their order is unpredictable. 00:43

2. There are (52!) possible arrangements of cards in a deck of 52 playing cards, a huge number that is also called "52 shriek." 02:07

3. If you riffle shuffle a deck of cards only 5 or 6 times, someone can still make money against you in a card-guessing experiment. 08:32

#### Facts You Didn't Know About Playing Card

The suits represent kings.

– Casino Floor

### Key Facts In This Video

1. Playing cards are believed to have originated in either China or Persia. 00:08

2. Thirteen cards in a suit represent the thirteen lunar months that occur in a single year. 00:37

3. Early playing cards were hand-painted, and only the affluent could afford to own them. 01:22

Curiosity Staff

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