Number–Letter Codes

This lesson builds on your knowledge of letter codes and introduces a trickier variation: questions where numbers and letters are mixed together. These questions test your ability to crack a code that uses both.

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What Are Number–Letter Code Questions?

In these questions, words are converted into codes made of numbers, letters, or a mix of both. You are given several examples of the code and must work out the system, then apply it to encode or decode a new word.

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Type 1: Letters Replaced by Numbers

Worked Example 1

Question: In a code, BEAR = 2-5-1-18. What is CAGE in the same code?

Step-by-step:

1. Look at the code: B=2, E=5, A=1, R=18.
2. These are just the alphabet positions: A=1, B=2, C=3, ... R=18.
3. Apply to CAGE:
   • C = 3
   • A = 1
   • G = 7
   • E = 5
4. Answer: 3-1-7-5

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Worked Example 2: Shifted Numbers

Question: In a code, CAT = 4-2-21. What is DOG in the same code?

Step-by-step:

1. Normal positions: C=3, A=1, T=20.
2. Code positions: 4, 2, 21.
3. Difference: each letter's position has been increased by 1 (3+1=4, 1+1=2, 20+1=21).
4. Apply to DOG:
   • D = 4, plus 1 = 5
   • O = 15, plus 1 = 16
   • G = 7, plus 1 = 8
5. Answer: 5-16-8

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Type 2: Two-Part Codes (Letters and Numbers Together)

Worked Example 3

Question: Study the following codes:

Word	Code
RED	R3D
BIG	B8G
SIT	S8T

What is the code for HEN?

Step-by-step:

1. Look at the pattern:
   • RED = R3D — the first letter stays, the last letter stays, the middle letter (E=5) becomes 3. Hmm, that does not match (E=5, not 3).
2. Wait, let me reconsider. E is the 5th letter. But the code shows 3. Let me check another: I is the 9th letter, code shows 8. And I in SIT also shows 8.
3. Pattern: the middle letter's position minus 2? E=5, 5-2=3. I=9, 9-2=7? No, that gives 7, not 8.
4. Let me try: E=5, code=3 (difference -2). I=9, code=8 (difference -1). That is not consistent.
5. Actually, let me look again. Maybe the number represents something else. R-E-D: the number between R and D. R=18, D=4. Difference=14? No, that is not 3.
6. Hmm, what about the number of letters between the first and last letters? R to D: R(18)...going backwards to D(4) = 14 steps. Not 3.
7. Let me try: vowels are replaced by a number. E=3... Could it be that the vowel is replaced by the number of sides on a triangle? That seems arbitrary.

Let me give you a cleaner, more typical example:

Question: Study the following codes:

Word	Code
CAT	C1T
DOG	D15G
PIG	P9G

What is the code for HEN?

Step-by-step:

1. The first and last letters stay the same.
2. The middle letter is replaced by its alphabet position number:
   • A = 1, O = 15, I = 9. Yes! That matches.
3. For HEN: the middle letter is E = 5.
4. Answer: H5N

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Type 3: Coded Pairs

Worked Example 4

Question: If these codes apply:

Letter	Code
A	7
B	3
C	9
D	1
E	5

What is the code for BEAD?