Twenty-two Foolish Primes
April 03, 2009
A set of disks numbered 1 through 100 are placed in a line in random order.
What is the probability that we have a partial derangement such that exactly 22 prime number discs are found away from their natural positions? (Any number of non-prime disks may also be found in or out of their natural positions.)
Give your answer rounded to 12 places behind the decimal point in the form 0.abcdefghijkl.
Written by gamwe6 who lives and works in San Francisco building useful things. You should follow him on Twitter