Two marks every shift, and in 2025 AAI asked this only as letter clusters. Convert to numbers, compare the gaps, and the odd one falls out in ten seconds.
Classification is the fastest mark in the reasoning section once you stop reading clusters as words.
Three of four items share a hidden rule. Your job is to find the rule, not to find something wrong with one item. Almost every wrong answer comes from spotting a different valid pattern that happens to isolate the wrong option.
Every classification question in the 2025 papers carried the same instruction in brackets: the odd one out is not based on the number of consonants or vowels, or on their position in the cluster. That single line eliminates the two things most candidates check first.
This is worth internalising because it converts an open-ended puzzle into a fixed procedure. There is only one thing to check, so check it immediately.
Find the rule that three items share. Never start by hunting for what is wrong with one item — that is how you talk yourself into the wrong option.
Given four clusters like FPJ, BLF, JTM, MWQ, convert every one to numbers, then write the two gaps beneath each. Three will match.
Write the four number triples in a vertical column, never side by side. Mismatched gaps are far easier to see when the numbers line up under each other.
Which cluster does not belong: CJE, HOK, RYT, MTO?
The harder version gives four pairs like KQ-WX. Here the internal gap is usually a decoy. The real rule connects the first cluster to the second: first letter to third letter, second letter to fourth.
Checking the internal gaps first is the classic trap, because the examiner often makes all four internal gaps identical. The information is in the cross-mapping.
The hyphen is the whole point. Jump over it. If you find yourself comparing K to Q inside the same cluster, you are on the decoy.
Which pair does not belong: KQ-WX, JP-TX, FK-PS, BG-LO?
Number sets did not appear in the 2025 shifts, but they have in earlier AAI and SSC-pattern papers, and they cost nothing to prepare. Run a fixed checklist rather than staring at the numbers.
Stop at the first test that isolates exactly one number. If two tests isolate different numbers, prefer the simpler one — examiners build these from a single rule.
Four words, in that order. Nine out of ten number classification questions are solved before you reach the word "digits".
Word sets ask for the shared category, and the trap is always a word that belongs to the same broad field but a different sub-category. Aviation vocabulary is worth knowing here, because AAI draws on it.
Name the category out loud for each word — surface, instrument, building, person, process. Three names will match. The word that shares the field but not the category is your answer.
The odd word is never from a totally different subject. It is from the same subject on a different shelf. Name the shelf, not the subject.
Four pages covering all four classification types, with a printable alphabet-position strip and ruled working space for your gap analysis. Print it, solve it, keep it.
Nine question formats, building in difficulty. Full solutions are in the downloadable PDF above.
| Column I — question type | Column II — first thing to do |
|---|---|
| (a) Three-letter clusters | (i) Map across the hyphen |
| (b) Cluster pairs | (ii) Name the category of each word |
| (c) Number sets | (iii) Write both gaps under each triple |
| (d) Word sets | (iv) Check squares, then cubes, then primes |
Live classes cover every reasoning, aptitude, English and GK topic straight from the real papers, with the shortcut for each question type drilled until it is automatic.