Competitive exam reasoning

Coding-Decoding Shortcuts and Alphabet Tricks

Coding-decoding questions reward careful bookkeeping. Convert letters to positions, identify whether the rule changes by position, and keep multi-step operations in the same order.

1

Use alphabet anchor positions

Work with A = 1 and Z = 26. Remembering E = 5, J = 10, O = 15, T = 20 and Y = 25 makes nearby letters quick to locate.

Solved exampleR is two places before T, so its forward position is 18.
Common trapA letter position is only a tool; it is not automatically the coding rule.
2

Find reverse positions with 27

Subtract a letter's forward position from 27 to get its reverse rank. Mirror-letter pairs also have positions that total 27.

Solved exampleD is position 4, so its reverse position is 23; D's mirror partner is W.
Common trapReverse rank and mirror substitution are related but answer different questions.
3

Track uniform and changing shifts

Compare every source letter with its coded letter. Test a fixed shift first, then position-based patterns such as +1, +2, +3.

Solved exampleIf DOG becomes FQI using +2, CAT becomes ECV.
Common trapWrap past Z correctly: Y + 3 becomes B.
4

Use common words as intersections

In statement codes, a word appearing in two statements must share a code appearing in both code groups, assuming a consistent one-to-one mapping.

Solved exampleIf ‘red blue’ is ‘ka mi’ and ‘blue green’ is ‘mi tu’, blue corresponds to mi.
Common trapTwo shared words can leave the mapping ambiguous; use another statement.
5

Preserve multi-step order

Some codes reverse a word and then shift letters. Apply the steps in the order established by the examples.

Solved exampleReverse CAT to TAC, then shift each letter by +1 to obtain UBD.
Common trapShift-then-reverse can produce a different result, so do not swap operations.

Frequently asked questions

What is the fastest way to remember alphabet positions?

Memorise five-position anchors—E, J, O, T and Y—and count only the small distance to nearby letters.

How do I handle shifts beyond Z?

Treat the alphabet as a cycle of 26 letters. Continue again from A after reaching Z.