nIt is important we think through the probabilities or expectations involved in what we have found in our search of the Gettysburg Address.
nWith a 21-letter alphabet and a 700-letter text, then (ignoring the fact that the letters occur with different frequencies), the chance a particular letter will occur is 700/21 = 33
nWe should expect about 33 occurrences of a given letter in our text, on average.