Coding–decoding for LIC AAO

Coding–decoding looks like guesswork until you notice that setters use a small set of rules again and again. Once you can recognise those rules, a letter-coding question takes under a minute and a sentence-coding set takes about two. The work is in the setup: knowing letter positions without counting on your fingers, and testing a suspected rule on every letter before you trust it.

The tools you need

• Positions: A = 1, B = 2 … Z = 26.
• Reverse position: 27 − position. So A = 26, M = 14, Z = 1.
• Opposite letters add up to 27: A–Z, B–Y, C–X, D–W, E–V, F–U, G–T, H–S, I–R, J–Q, K–P, L–O, M–N.
• Memory anchors: E J O T Y are 5, 10, 15, 20, 25. From any anchor, count one or two steps.

The method for letter codes

1. Write the word and its code one above the other, letter under letter.
2. Check for a reversal first. If the code's letters look like the word's letters shifted but in reverse order, reverse the code before comparing.
3. Find the change for each letter in positions: +1, −2, opposite, and so on.
4. Test the rule on every letter. A rule that fits three letters of four is the wrong rule.
5. Apply it to the new word, in the same order of operations.

Five common patterns

Pattern 1: shift, then reverse. SAFE is coded as FGBT.

• Shift each letter +1: S→T, A→B, F→G, E→F gives TBGF.
• Reverse: FGBT.
• So RISK → SJTL → LTJS.

Pattern 2: reverse positions as numbers. Each letter becomes its position counted from Z.

• LIC → L = 15, I = 18, C = 24 → 15 18 24.

Pattern 3: opposite letters. Each letter is replaced by its opposite.

• LIFE → L↔O, I↔R, F↔U, E↔V → ORUV.

Pattern 4: alternate shifts. The first letter moves +1, the second −1, the third +1, and so on.

• CASH → C+1 = D, A−1 = Z, S+1 = T, H−1 = G → DZTG.
• Note the wrap-around: one step back from A is Z.

Pattern 5: sentence coding. Each word has its own code, and the codes may appear in any order.

• "claim is settled" → "ta ri po"
• "policy is active" → "ri mu sa"
• "claim policy renewed" → "po sa ke"

Solving: compare statements two at a time. The word they share must have the code they share.

• "is" is in statements 1 and 2; the common code is ri.
• "claim" is in 1 and 3; the common code is po.
• "policy" is in 2 and 3; the common code is sa.
• What remains in each statement: settled = ta, active = mu, renewed = ke.

Spotting the rule type quickly

A position swap. MONEY is coded as NOMYE. Compare letter by letter: the first three letters, MON, appear reversed as NOM, and the last two, EY, appear reversed as YE. So PLANS becomes ALP + SN = ALPSN. No letter changed, only its place, which is the clue that sends you looking for blocks.

When a code cannot be found

Sometimes two words always appear together. Then their codes cannot be separated, and the right answer is "cannot be determined". Look at this set:

• "pay premium today" → "zo ka ri"
• "premium due today" → "ri ka pe"
• "due date extended" → "pe mo su"

"premium" and "today" appear together in statements 1 and 2, which share ka and ri. Nothing separates them, so neither code is fixed. The same is true of "date" and "extended" (mo, su). Two codes are fixed: due = pe (statements 2 and 3) and pay = zo (what is left in statement 1).

Practice set

1. Using Pattern 1 (shift +1, then reverse), code LOAN.
2. Using Pattern 2 (reverse positions), code LOAN.
3. In the Pattern 5 set, what is the code for "renewed"?
4. Using Pattern 3 (opposite letters), code BOND.
5. Using Pattern 4 (alternate +1, −1), code FUND.
6. In Pattern 1, a word is coded as NJBMD. What is the word?
7. In the "pay premium today" set, what is the code for "pay"?
8. In the same set, what is the code for "premium"?

Answers

1. OBPM. Shift: MPBO. Reverse: OBPM.
2. 15 12 26 13. L is 12th, so 27 − 12 = 15; O is 15th, so 12; A = 26; N is 14th, so 13.
3. ke.
4. YLMW. B↔Y, O↔L, N↔M, D↔W.
5. GTOC. F+1 = G, U−1 = T, N+1 = O, D−1 = C.
6. CLAIM. Undo the steps in reverse order: reverse NJBMD to DMBJN, then shift each letter −1 to get CLAIM.
7. zo. Statement 1 is zo, ka, ri; ka and ri belong to premium and today.
8. Cannot be determined. It is ka or ri, and no statement separates premium from today.

A quick routine for the exam hall

• Write the alphabet with positions once on your rough sheet at the start of the section. It takes 30 seconds and saves many more.
• For decoding, undo the steps in reverse order: the last step applied is the first one you undo.
• For sentence coding, tick off each word and code as you fix them.

What to do next

• Learn the opposite-letter pairs and the EJOTY anchors until you can say them without counting.
• Do one sentence-coding set and five letter codes daily for a week.
• Coded symbols also appear in inequalities and blood relations. Practise them together.