Coding–Decoding • Topic 2 of 4

Number Coding

Number coding maps each letter to a number — usually its alphabet position (A=1), sometimes position×k or position+k, or a sum of positions for the whole word. Decode by writing positions under the letters.

Three common number rules

RuleExample (for "CAB")
Position (A=1…Z=26)C=3, A=1, B=2 → 3-1-2
Position × k×2: C=6, A=2, B=4 → 6-2-4
Sum of positions3 + 1 + 2 = 6 (one number for the word)
When a word maps to one number, test the sum of letter positions first (it is the most common), then the product. Writing positions under each letter makes the pattern obvious in seconds.

✅ Solved examples

1. If A=1, B=2 …, code CAB.
C=3, A=1, B=2 → 3-1-2.
2. If A=2, B=4, C=6 …(position×2), code DAD.
D=8, A=2, D=8 → 8-2-8.
3. If the code of a word is the sum of letter positions, find the code of BAD.
B(2)+A(1)+D(4) = 7.
4. If CAT = 24 by position-sum, verify.
C(3)+A(1)+T(20) = 24. Correct.

✏️ Practice — try these, take hints as needed

1. A=1…: code FAD.
Positions.
F=6,A=1,D=4.
—
6-1-4
2. Position-sum: code of ACE?
1+3+5.
—
—
9
3. Position×3: code of CAB?
C=9,A=3,B=6.
—
—
9-3-6
4. Position-sum: code of DOG?
4+15+7.
—
—
26
5. A=1…: code BED.
2-5-4.
—
—
2-5-4

📝 Topic test — 8 questions

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