Letter codes & shifts
Crack the example before you touch the options.
← All countdown tipsMany 11+ codes are a shift cipher: every letter moves the same number of steps along the alphabet, in the same direction. Crack the shift from one example, then apply it to every letter of the new word — in order.
Your reference: the alphabet, A–Z
Count along this line to work out any shift — for example, D to E is one step forward.
A–Z with position numbers (A = 1 … Z = 26)
Some codes swap letters for these numbers — the shift works exactly the same way, just written as digits.
Picture it: DOG shifted by +1
- Every letter moves the same amount — here, one step forward each time
- D→E, O→P, G→H: the shift never changes mid-word
- Work out the shift from a given example pair before you touch the target word
Remember — the method
- Compare one letter of the example word with its code letter — count the steps and the direction.
- If a second letter pair is given, check the same shift fits it too.
- Apply exactly that shift to every letter of the target word, in order.
- Watch for wrap-around: after Z the alphabet starts again at A (and going the other way, just before A is Z).
- Some codes don’t use one shift for the whole word — each letter can have its own shift, sometimes repeating in a cycle. Write the shift under every letter before you decode.
The wrap-around trap
Shift +3 applied to YES: Y is near the end of the alphabet, so it wraps back to the start.
YES → BHV (Y, 25th letter, +3 = 28, wraps to 2 = B)
Trickiest of all: a different shift for each letter
Not every code uses one steady shift. Some give (or hide) a different shift for each letter, often a short pattern that repeats: +3, −2, +1, −1, +3, −2, … Read the shifts left to right, one per letter, and keep going in the same order if the word is longer than the pattern.
PLAY → SJBX using shifts +3, −2, +1, −1 (a different shift under every letter, in order)
The pattern can repeat past its own length — and can wrap below A too
GARDEN, cycle +3, −2, +1, −1 repeating: A − 2 goes past the start, so it wraps round to Y — the same wrap-around idea, just running backwards.
Exam trap
Mixing up encode vs decode. If a shift of +1 turns a word into its code, then turning that code back into the original word needs the opposite shift, −1 — not another +1.
✗ Shifting +1 again on the code
→ E, C, V (wrong — moves further away)
✓ Shifting −1 to decode
→ C, A, T (correct original word)
Question patterns you might see
Same shift idea, dressed up differently — from a stated shift, to numbers standing in for letters, to a different shift for every letter.
1 · Simple — Encode with a stated shift
“If the shift is +2, what is the code for BEE?” B→D, E→G, E→G → DGG.
2 · Simple — Decode with a stated shift
“UWP is coded with shift +2. What is the original word?” Shift each letter back by 2: U→S, W→U, P→N → SUN.
3 · Medium — Work out the shift, then apply it
“If PIG codes to QJH, what does CAT code to?” P→Q, I→J, G→H is +1 throughout. Apply +1 to CAT: C→D, A→B, T→U → DBU.
4 · Medium — Wrap-around word
“What does YES become with shift +3?” Y wraps past Z back to B: Y→B, E→H, S→V → BHV.
5 · Trickier — Two examples must agree
You are told B→E and K→N. A shift of +3 fits both (B is 3 steps before E, K is 3 steps before N) — a guess of +2 would fit B→D but fails on K→N. Always check a shift against every example given, not just the first.
6 · Trickiest — Numbers standing in for letters
Using A = 1 … Z = 26, a code adds 3 to each letter’s position. DOG → D(4), O(15), G(7) → codes 7, 18, 10. So the numbers 7, 18, 10 decode by subtracting 3: 4, 15, 7 → D, O, G. It is the same +3 shift, just written as digits instead of letters.
7 · Trickiest — Mixed shifts, one per letter
“Code PLAY using shifts +3, −2, +1, −1 (one per letter).” P→S, L→J, A→B, Y→X → SJBX. Each letter gets its own shift from the list, in order — not the same shift repeated.
8 · Trickiest — A repeating shift cycle, longer than the pattern
“Code GARDEN using the repeating cycle +3, −2, +1, −1.” Six letters, four shifts — so the cycle restarts after the 4th letter: G→J (+3), A→Y (−2, wraps below A), R→S (+1), D→C (−1), E→H (+3 again), N→L (−2 again) → JYSCHL.
Coach tip: write the alphabet A–Z along the top of your working — it makes counting the shift (and spotting wrap-around) much faster under time pressure.
Tomorrow (D-20): reverse percentages.
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