I have previously looked at a similar calculation based on 12 from 20 out of 312 Humbly I'll accept correction from you as required :- Since there are 20 chances in 312 of picking the first correct card the answer is 1 in 15.6 If first pick is correct i then there is a 19 chance in 311 to pick the next correct card = 1 in 16.4 chance. For the first 2 correct picks = a 1 in 255 chance (15.6 x 16.4) So it escalates for the next 10 picks. I remember that you were more likely to win 6 from 45 lotto twice in a row than picking 12 from 20 out of 312