probability
did you know a deck of cards has an absurd number of orders?
52 ordinary cards create a number with 68 digits.
52!
about 8.07 × 10⁶⁷ possible orders
all 52 cards are distinct, and their order matters.
- 52 first choices
- 51 next choices
- multiply to 1
the idea
a standard 52-card deck has about 8.07 × 10⁶⁷ possible orders. that is an eight followed by another 67 digits. the deck looks small because you see only one arrangement at a time.
how it works
even a much smaller deck grows quickly: three distinct cards have six orders; ten have 3,628,800. adding one more card multiplies the previous count by the new deck size.
go deeper
where does that enormous number come from?
a standard 52-card deck has about 8.07 × 10⁶⁷ possible orders. that is an eight followed by another 67 digits. the deck looks small because you see only one arrangement at a time.
there are 52 choices for the top card. once it is placed, 51 choices remain for the next position, then 50, all the way down to one. each choice branches into more possibilities.
multiply the choices, not the cards
even a much smaller deck grows quickly: three distinct cards have six orders; ten have 3,628,800. adding one more card multiplies the previous count by the new deck size.
a uniformly random full-deck order has probability 1/52!. this makes any one specific arrangement fantastically unlikely, although some arrangement must occur every time.
what is a factorial?
the exclamation mark means multiply every positive whole number up to the number before it. it is notation for repeated choices, not extra excitement.
52! = 52 × 51 × 50 × … × 2 × 1 ≈ 8.07 × 10⁶⁷
does every shuffle explore those orders fairly?
- no. a careless shuffle can leave clusters intact, and a perfectly repeated mechanical shuffle can cycle through a small set of orders.
- the huge possibility count does not prove your arrangement has never occurred. that claim also depends on the history and randomness of actual shuffles.
sources & further reading
concepts: permutations · factorials · large numbers
2 minute read