Number-Letter Coding

In number-letter coding, letters are replaced by numbers (or vice versa) according to a fixed rule. The most common rule is A=1, B=2, C=3 … Z=26. Some questions reverse it: A=26, B=25 … Z=1. Others use only odd or even positions, or the position of the letter in reverse alphabetical order. The question usually gives you a coded example so you can work out the exact rule before answering.

1. Assign standard positions to the alphabet: A=1, B=2, C=3 … Z=26. Write this out if needed.
2. Look at the given example: if CAT = 3-1-20, the rule is standard forward positions.
3. If CAT = 24-26-7, check: C(3) → 26-3+1 = 24. That means the rule is reverse positions (A=26, B=25 etc.).
4. Apply the confirmed rule to the new word or number sequence.
5. Write the answer clearly, separating each number with a dash.

Example 1 (A=1 rule): If the code for DOG is 4-15-7, what is the code for CAT?

• C=3, A=1, T=20.
• Code: 3-1-20.

Example 2 (reverse rule, A=26): If the code for BAD is 25-26-23, what is the code for CAB?

• Check: B=25 means A=26, B=25, C=24, D=23. Rule confirmed.
• C=24, A=26, B=25.
• Code: 24-26-25.

• Assuming the rule is always A=1. Always verify with the given example first.
• Confusing the number for the position with the number for a reversed position — they look similar for letters near M (the middle).
• Missing a letter: count carefully when the word has repeated letters (e.g. BALL = 2-1-12-12).

1. Using A=1 … Z=26, decode the number sequence 13-1-20-8.
2. If ACE is coded as 26-24-22 (reverse rule), what is the code for BIG?