To encode the following message the text was first written as pairs of letters ignoring the
spaces between the words. For example John Brown would be written jo hn br ow nz
where the z is added because there are an odd number of letters.
The letters of the alphabet are numbered
and each pair of letters
is replaced by a pair of numbers. There are
pairs of numbers. It is possible to
store the codes for all 676 pairs and look them up as needed but much more efficient to use a
decyphering formula.
Each pair of numbers
is encoded as another pair of numbers
where