We draw 2 cards from a deck of 52 cards. what is the probability that both are queens?

Use combination

There are 4 queen cards in a deck of 52 cards

Probability = 4C2 / 52C2

I calculate 4C2 first

4C2 = 4! / (2! 2!)

4C2 = (4 * 3 * 2 * 1) / (2 * 1 * 2 * 1)

4C2 = 6

Then I calculate 52C2

52C2 = 52! / (50! 2!)

52C2 = (52 * 51) / 2

52C2 = 1.326

Hence, the probability is

Probability = 4C2 / 52C2

Probability = 6/1,326

Probability = 1/221