[Neil Stevens]

Probability of pulling an ace exactly once out of 13 tries:

(1/13)^1 * (12/13)^12 * 13 = 38%

(chance of getting the ace once) * (chance of getting non-ace 12 times) * (number of ways to pull once ace)

Probability of pulling an ace exactly twice:

(1/13)^2 * (12/13)^11 * 78 = 19%

Probability of pulling no aces:

(12/13)^13 = 35%

Hope this helps (and I hope I made no errors!)