Coding-Decoding — Letter Shifts, Reverse Codes and Number Codes

In coding-decoding, a word is written in a secret way. You find the rule from one example, then apply it to another word.

1. Letter shift codes

Example 1

If COLD is written as DPME, how is WARM written?

Each letter moves +1: W→X, A→B, R→S, M→N → XBSN.

Example 2 — changing shifts

If PLANT is coded as QNDRY, how is GREEN coded?

P→Q (+1), L→N (+2), A→D (+3), N→R (+4), T→Y (+5). Apply to GREEN: G+1 = H, R+2 = T, E+3 = H, E+4 = I, N+5 = S → HTHIS.

Always write the positions of both words in two rows and subtract. The rule appears immediately.

2. Opposite (reverse) letter codes

The opposite of a letter is the letter at the same distance from the other end: A↔Z, B↔Y, C↔X … positions add up to 27.

Example 3

If GOLD is coded as TLOW, how is SILVER coded?

G(7)→T(20): 7 + 20 = 27 ✓ — opposite letters. SILVER → S↔H, I↔R, L↔O, V↔E, E↔V, R↔I → HROEVI.

3. Reversing the word

Example 4

If BRAIN is coded as NIARB, how is HEART coded? → written backwards → TRAEH.

Sometimes the word is reversed and shifted. Check both.

4. Number codes

Example 5

If CAT = 24 (3 + 1 + 20), what is DOG?

D(4) + O(15) + G(7) = 26.

Example 6

If BAD is written as 214, how is FACE written? → positions → 6135.

5. Sentence (word) codes

Several sentences are coded word by word. Find the word that appears in two sentences — its code is the code that appears in both.

Example 7

"sky is blue" → "ta na ri"; "blue is nice" → "ri po ta". What is the code for "nice"?

"is" and "blue" are common to both sentences, and "ta" and "ri" are common codes. So "nice" = the remaining code of the second sentence = po. (And "sky" = na.)

Common mistakes

• Counting letters on fingers — use positions and EJOTY.
• Forgetting to "wrap around": after Z comes A again (Y + 3 = B).
• In sentence codes, assuming the order of words matches the order of codes. It usually does not.

Quick recap

• Write positions of the word and its code; subtract to find the rule.
• Opposite letters add to 27.
• Check reversing, shifting and both.
• Sentence codes: match common words with common codes.