Prob of not drawing card in x trials...help

[R Gibert]

46.311% confirms your other calc with the following more general program:
<font class="small">Code:</font><hr /><pre>
from random import *

n = 100000
t = 90
k = 52
c = 0
deck = range(52)
for j in range(n):
m = [False]*52
for i in range(t):
d = sample(deck,2)
m[d[0]] = True
m[d[1]] = True
if len(filter(lambda x: x == False, m)) &lt; 2:
c += 1
print 1 - float(c)/n
</pre><hr />
I traded efficiency for something more readable. Retaining the old approach was workable, but the bit twiddling would have produced an ugly result.