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.