Verbal Reasoning · Applying a mirror alphabet code
Break the code FHVW
COULD became XLFOW. The message came back as FHVW. Use the same code to work out the real word.
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Why this works
In a mirror code the alphabet is folded in half: A pairs with Z, B with Y, and on inwards until M pairs with N. That is why USED and FHVW go together, and why the same fold turns the code back into the word. Two things make this fast. The first is that the positions of a pair always add up to 27, so a letter at position 7 pairs with the letter at position 20 without any counting along. The second is that the letters have very different costs. A, Z, M and N are free because they sit on a landmark, while U sits several steps from every landmark there is, and that is the letter worth checking twice. A mirror code is also its own undoing, so there is no separate method for reading a message and writing one. Whatever you do to a letter, doing it again brings the letter back.
Helping a child through Break the code FHVW
Hints, least revealing first
- Write the alphabet forwards, then write it backwards underneath so A sits over Z and B sits over Y. Every letter now has a partner.
- Counting works from either end. U is the 21st letter from the start, so its partner is the 21st letter from the end.
- The mirror undoes itself. Pairing up a coded letter gives you the real one, exactly the same way round.
When they finish it: “Mirror code cracked!”
2 11+ skills this exercise practises
Each of these has its own page, with a worked example on it.
- Apply mirrored alphabet pairingMap letters through a stated or inferred reversed-alphabet pairing.
- Decode a letter-word codeInfer a positional substitution rule and apply it to one new word.
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