[keikiwai]

48/52 * 47/51 * ... * 37/41 = .338

A shortcut would be to see what the probability of all 4 Aces not being in the first 12 cards is. The probability fo 1 A not being in the first 12 cards is 40/52. This has to happen 4 times so you have (40/52)^4 = 35%

It is not exactly the same since I ignored the fact that if the 1st A is not in the top 12 it reduces the chance of the others not being in the top 12. Improved it is

(40/52)*(39/51)*(38/50)*(37/50)= .338

Exactily the same as Atticus (-Kanobe)!

Peter.