Probability of getting 2 consecutive cards

combinatoricspermutationspigeonhole-principleprobability

2 cards are drawn at random from the a deck of 52 (without replacement). Ace = 1, Jack = 11, Queen = 12, King = 13. How would you find the probability of getting 2 cards of consecutive numbers?

Note: It is not a cyclic so 1 is not a consecutive of King

Best Answer

Just sum the probabilities of $1-2, 2-3, 3-4,..., 12-13$

probability to get $1-2$ = $2* \frac{4}{52}*\frac{4}{51}$

The total probability = $\frac{2*12*4*4}{52*51}$