Coding–Decoding is guaranteed marks: 2–4 questions in every SSC and RRB reasoning section, and every question belongs to one of nine mechanical patterns. Learn the nine, and this topic never surprises you again. Keep the alphabet positions handy - the trick EJOTY (E=5, J=10, O=15, T=20, Y=25) lets you find any letter's position in two seconds.
Q: If CAT = DBU, then DOG = ? Each letter moves +1 → EPH. Always test the shift on two letters, not one - mixed shifts (+1, +2, +3…) are the common upgrade of this type.
A↔Z, B↔Y, C↔X… (positions sum to 27). Q: If SUN = HFM, then MOON = ? Each letter maps to its opposite → NLLM. Shortcut: remember the pairs AZ, BY, CX, DW, EV, FU, GT, HS, IR, JQ, KP, LO, MN.
Q: If BAD = 7 (2+1+4), then CAB = ? → 3+1+2 = 6. Variants: positions multiplied, or reversed positions (A=26). If the simple sum fails, test reversed positions next.
"If sky is called sea, sea is called water, water is called air… where do fish live?" Fish live in water, and water is called air - answer the real-world fact, then translate once. The trap is translating twice.
"'pit nac mo' means 'red sweet fruit', 'mo hi cha' means 'fruit is good'…" Find the common word between sentences: 'mo' is common and 'fruit' is common → mo = fruit. Eliminate pair by pair like simultaneous equations. Write the sentences one under another - solving these in your head causes the errors.
A grid gives codes for digits/letters with conditions ("if the first element is a vowel and the last a consonant, swap their codes"). Pure carefulness: apply conditions in the given order, and check whether YOUR row triggers a condition before copying codes mechanically.
"How many symbols are immediately preceded by a digit and followed by a consonant?" Scan the string once left to right, marking hits - never scan for each element separately. In the exam, underline with the mouse pointer while counting.
Q: If PAINT = 74128 and EXCEL = 93596, then ACCEPT = ? Match repeated letters to repeated digits (A=4? check across both words). These test mapping consistency - build the letter→digit table first, then read the answer off.
Codes built from word properties: number of letters, first/last letter positions, vowels count. Q: If DELHI = 5×(number of letters) = 25 pattern fails, test: sum of first and last letter positions, letters × 2 ± k, product of vowel positions. Have a fixed testing order - (a) position sum, (b) letters count × k, (c) first+last, (d) reverse positions - and you'll crack these inside a minute.
Attempt coding questions early in the reasoning section - they're deterministic, unlike puzzles that can eat five minutes. If a pattern doesn't reveal itself in 45 seconds through the standard tests above, mark for review and move on; these questions are cheap when they click and expensive when they don't. Drill all nine types in timed sets on Pareeksha's Coding–Decoding practice until the pattern-recognition is instant.
EJOTY marks the alphabet positions E=5, J=10, O=15, T=20, Y=25. Any letter's position is found by counting one or two steps from the nearest anchor - far faster than counting from A.
Typically 2–4 questions in SSC CGL/CHSL/MTS reasoning and 2–3 in RRB NTPC/Group D - and virtually all belong to the nine standard types covered here.
Pairs whose alphabet positions sum to 27: A–Z, B–Y, C–X, D–W and so on. Questions on reverse-alphabet coding are solved instantly if you memorise these thirteen pairs.