Number-Based Reasoning Series

The Reasoning section carries its own number items — odd-one-out among a group of numbers and number analogy — which test pattern-spotting rather than heavy calculation. These differ from the Numerical section's arithmetic series: here the numbers are small and the relationship is a neat logical rule you must name. In SBI Clerk they add two to four quick marks, and the trick is a fixed checklist of patterns you run through until one fits. Because the numbers stay small and clean, the work is recognition rather than arithmetic, so a candidate who has drilled the common patterns answers almost on sight while an unprepared one burns a minute testing random ideas.

Run a Fixed Pattern Checklist

When you see a group of numbers, test the usual suspects in order: are they all prime, all perfect squares, all cubes, all multiples of a number, or do their digits share a property such as summing to the same total? Running the same short checklist every time means you stop guessing and start eliminating. The odd one out is the single number that breaks the rule the other four obey. If the first pass finds no pattern, widen the checklist to one-operation links — each number one more than a square, or each the product of consecutive integers — but keep the tests in a fixed order so your eye never wanders and no second is wasted on random trial.

Odd One Out in Numbers

Find the rule the majority follow, then name the misfit. In 16, 25, 36, 49, 63 the first four are perfect squares and 63 is not, so 63 is the odd one. Watch for two competing patterns — sometimes four numbers are even and one odd while a deeper square-or-prime rule is the real intended answer, so prefer the stronger structural pattern over a shallow even-odd split. A reliable tie-breaker is to ask which reading leaves exactly one number outside the rule: the intended pattern isolates a single misfit, so a rule that would exclude two numbers is almost certainly not the one the setter had in mind.

Checklist: prime? square? cube? common multiple? equal digit-sum? one operation apart?

Number Analogy

Number analogy gives a pair like 7 : 50 and asks you to complete a second pair by the same relationship. Test simple links: is 50 near 7 squared plus one (49 + 1)? Then apply the same to the target. Analogy relationships are usually one clean operation — square, cube, double-and-add-one, or reverse the digits — so name that operation from the given pair and copy it exactly onto the second pair. When one operation does not land cleanly, check a two-step link such as square-then-subtract, but resist inventing an elaborate rule: the intended relationship is nearly always the simplest one that fits, and options are spaced so that the clean operation points to a single answer without ambiguity.

Solved Examples

Q1 (odd one): 8, 27, 64, 100, 125. Cubes are 8, 27, 64, 125; 100 is a square, so 100 is the odd one. Q2 (analogy): 6 : 37 :: 9 : ? Pattern is n squared plus one: 36 + 1 = 37, so 81 + 1 = 82.

✗ Splitting 8, 27, 64, 100, 125 by even and odd numbers  |  ✓ Spotting the cube pattern and naming 100 as the non-cube