This "Probability" problem has stumped me for several weeks:
If I randomly select a 20 character password from a set of 256 characters composed of:
4 sets of lower case letters (104),
3 sets of Upper case letters (78),
7 of each number in 0..5 (42) and
8 of each number in 6..9 (32)
What are the chances a second random 20 character selection will match the first?
P(M,N) means the probability of M items taken N at a time, order counts.
C(M,N) means the # of combinations of M items taken N at a time (order is n/a)
Many thanks . . .