Puzzle reference pages » A=1, B=2 ... Z=26
assembled by Quincunx
In most cases, when someone creates a puzzle for a contest or competition like MIT's Mystery Hunt, the solution to that puzzle is a piece of text, either a word or a phrase, perhaps an instruction. (Some other solutions are numbers, and I suppose some could be pictures.) But when a puzzle is numberbased, how does one get from a number or group of numbers to a word or phrase?
The most useful tool is a substitution cipher where each letter of the alphabet is represented by a number which corresponds to that letter's position in the alphabet. In simplest terms, this can be written as A=1, B=2 ... Z=26. Since A is the first letter of the alphabet, it is represented by the number 1. B, the second letter, is represented by 2. Z, the last of the 26 letters in the alphabet, is represented by 26.
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z 
1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26 
So if, upon solving a puzzle, you find yourself left with a series of numbers as an apparent "solution," try the A=1, B=2 ... Z=26 cipher on it to see if a word or phrase is represented by the numbers.
For example, here's a simple puzzle:
¤¤¤¤¤¤¤¤ ¤¤¤¤¤¤¤¤ ¤¤¤¤¤¤¤ 
¤¤ ¤¤ ¤ 
¤¤¤ ¤¤¤ ¤¤¤ 
¤¤¤ ¤¤ ¤¤ 
¤¤¤ ¤¤¤ ¤¤ 
¤¤¤¤¤¤¤ ¤¤¤¤¤¤¤ ¤¤¤¤¤¤ 
If you want to solve this puzzle on your own, do so before reading further.
There are several ways to look at this diagram. If you ignore the rows within each box and just count the number of symbols, you'll count 23, 5, 9, 7, 8 and 20. Look up the letter that matches each number and see if it spells a word.
Not every set of numbers using the A=1, B=2 ... Z=26 cipher in puzzle rallies will be a clear series of numbers between 1 and 26 inclusive. Here are some other ways words and phrases can be represented by numbers using the cipher.
0312010913 – in this case, there are five pairs of digits with the spaces between them removed. Zeroes have been inserted where needed to make the numbers two digits. This number broken into pairs is 03, 12, 01, 09, 13 – you can decipher it from there.
3121913 – this is the same number as the previous example, with leading zeroes omitted. Note that it becomes very difficult to decipher this. Even knowing that numbers need to fall between 1 and 26, which numbers form pairs? Is 12 a number? 21? 19? 13? If it is read as 3, 1, 21, 9, 1, 3, it spells the gibberish CAUIAC; if read as 3, 1, 2, 19, 13, it spells CABSM. Solving this would likely come down to trial and error. If you run into this, perhaps you've failed to notice a symbol which divides the numbers... or perhaps the puzzlecrafter is just feeling sadistic.
22 01 34 01 12 24 01 – deciphered as it appears, this yields VA?ALXA... what's that 34 doing there? If you're familiar with bases, and you've noticed that all the digits are 0 to 4 inclusive, you might try reading these numbers as written in base 5. The 22 becomes (2x5 + 2x1 = ) 12 in base 10. The 01 becomes (0x5 + 1x1 = ) 1 in base 10. And that 34 becomes (3x5 + 4x1 = ) 19 in base 10. So far, 12, 1, 19 = L, A, S... can you figure out the rest? (Note: the largest twodigit number in base 5, 44, is 24 in base 10... so Y and Z can't be used as normal.)
002 102 021 013 020 110 – same as the last example, but uses base 4. So 002 becomes (0x4² + 0x4 +2x1 = ) 2; 102 becomes (1x4² + 0x4 +2x1 = ) 18, and so on. (The largest threedigit number in base 4, 333, is 63 in base 10, which is sort of overkill, especially considering the next example.)
200 120 002 120 202 – same as the last two examples, but uses base 3. So 200 becomes (2x3² + 0x3 +0x1 = ) 18; 120 becomes (1x3² + 2x3 +0x1 = ) 15, and so on. (The largest threedigit number in base 3, 222, is 26 in base 10, making this perfect for the A=1, B=2 ... Z=26 cipher! The unused 000 can be used as a space character.)
00011 01100 10101 00010 – if you've noticed the pattern in the past three examples, figuring out this one should be simple. (The largest fivedigit number in base 2, 11111, is 31 in base 10, so a few numbers will be unused.)
This grid is a graphic representation of the previous example. Each row of five cells stands for one number, with a filled cell for 1 and a blank cell for 0. 
Here are two more uses of the A=1, B=2 ... Z=26 cipher that haven't been specifically covered above. The solutions are the names of two characters in Shakespeare's "Hamlet." Best of luck!
[0] +18, 3, +4, 14, +9, 11, +15, 17, +13, +6, +6

Hint: 1 49171514112 1311811 5172111219 69225 225182093112 131181119 
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