How do you guess a card without looking?

Answer 1

It's easy enough to GUESS a card without looking at it. Pick any card. Ok, I guess its the 3 of Diamonds. Done. However, guessing a card, or sequence of cards correctly, is a bit trickier.

Lets assume that we are going to use a standard deck of cards (52, no Jokers) and you will pick one at a time, and I will guess what it is. In this example, we're going to assume that you return the card to the deck. This is an important clarification as it drastically changes the probabilities.

The first time, I have a 1/4 chance of guessing the suit, a 1/13 chance of guessing the value, and a 1/52 chance of guessing both correctly.

The second time, the chances of me getting the card correct are again 1 in 52, however, getting both guesses right means I have a 1 in 2704 chance (52 x 52).

The third time, again, I have a 1 in 52 chance of guessing the card correctly, but to get the whole sequence correct, my odds have reduced to 1 in 140608 (52 x 52 x 52).

And so on.

Being able to guess even the first 6 cards correctly is a rather astounding feat, but is not in and of itself significant. Just like someone winning the lotto, there's always a chance of "beating the odds". But it does grow exponentially less likely.

When you do see someone who manages this feat MULTIPLE times, you are probably dealing with some sort of trick: a marked deck, a forced series of cards or some other factor that you aren't aware of.