If one selects eight different letters from the alphabet, they can be arranged in 8! = 40320 different ways. If one allows any subset of letters from 1 through 8 to be chosen, the number of arrangements increases from 8! + (8)7! + (8x7/2) 6! + ... + 8 = 109600. Obviously, no more than a tiny fraction of these arrangements is likely to form words, and choosing a set of eight letters and seeking to verify as many as possible as real words would be a lifetime's work.
Word Ways: Vol. 15
, Article 10.
Available at: http://digitalcommons.butler.edu/wordways/vol15/iss1/10