Cracking The Alphabet

Posted 10 Jun, 2013

In our codeword puzzles, each letter is allocated a number, and knowing the relationship between numbers and letters leads you to the words in the grid. This is very similar to the method that cryptologists use when trying to crack secret codes.

Expert code-breakers start by counting how often each individual symbol or letter occurs in the message. No matter what sort of text you have – whether it's from a Shakespeare play or from a tabloid newspaper article – the letters of the alphabet occur roughly at the same frequency in English.

The commonest letter is E. In a longish piece of text, you would expect to find more than 50 times as many Es as Js or Qs. In fact, about 11 per cent of the individual letters in the text will be E. So, when cracking a code, cryptologists often assume that the commonest symbol represents E.

The next commonest letters in order are A, R, I, O, T, N, S, L with a frequency of around five or six per cent. Then come C, U, D, P, M and H (three or four per cent). Slightly less common, with a frequency of about two per cent, are G, B, F and Y. The characters W, K and V appear once in around every 100 letters, and the rarest letters of all are X, Z, J and Q.

The frequencies above refer to the appearance of the letters anywhere in the text, but if you look at the first and last letters of words, you get a different picture. E begins only four per cent of common English words, whereas nearly 12 per cent of words begin with S and just under 10 per cent begin with C.

E is quite common at the end of a word; it's the last letter of about 12 per cent of common words. The commonest letter of all in this position is S. If you took a text of several hundred words, around 25 per cent of them would end in S – that's because of plurals, of course. Although Y is fairly rare at the start or in the middle of words, it is commonly found at the end – it is the final letter of roughly 10 per cent of words.

This information is very useful to cryptologists, but it won't necessarily be helpful to you when you're doing our codeword puzzles. Be warned! Here at Puzzler we have some fiendishly devious compilers, who go out of their way to design puzzles with words that defy all the rules!

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