User:Tray Golush

How to pick a card at random card
To most, choosing a random card is merely selecting a card from a spread of cards. Although the choice feels like free will, mathematician Dave Bayer has proven (2% margin of error) that there are only three spots in a spread of cards that a person will select from. The middle 10 cards, 5 card from the left [Bottom of Spread], and 5 cards from the right [Top of Spread]. In fact, women were 88% more likely to choose a card near the bottom of the spread than men. And men were 70% more likely to choose a card from the middle than they were from the Bottom or Top of the spread of Cards.

Persi Diaconis and Dave Bayer concluded that the number of shuffles needed to randomize a deck is between five and seven.

Combinations of cards

There are exactly 52 factorial (52!) possible orderings of the cards in a 52-card deck. This is approximately 8×1067 possible orderings. The magnitude of this number means that it is exceedingly improbable that two randomly selected, truly randomized decks, will ever, in the history of cards, be the same.

Vigintillion

80,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

Random Way to pick a Card
The following procedure was discovered by Persi Diaconis in his study of randomness to be the most effective in achieving a random card.

1. Have deck shuffle 5-7 times to ensure randomness.

2. Cut off a small group of cards from the top of the deck. (~1/3 of the cards)

3. Count how many cards were cut to.

4. From the face of the deck count down the number of cards that you counted in step 3. For example if you cut off 11 cards, you would count down to the 11th card from the face of the deck.

Although cumbersome, utilizing multiple variables to choose a card ensures its randomness.

Best way to shuffle a deck of cards
Although Diaconis and Bayer concluded that 5-7 riffle shuffle ensure randomness of playing cards, Yogi Hersner, a Harvard student at the time, discovered randomness of a deck can be achieved in one shuffle.

1. Divide the deck into multiple piles (8 or more) into 2 rows. (Figure X)

2. Shuffle piles 1 & 2 togther, then 3 & 4, then 5 & 6 and finally 7 & 8.

3.