In the following number-pairs, the second number is obtained by applying certain mathematical operations to the first number. In three of the four pairs, the same pattern is applied and hence they form a group. Select the number-pair that DOES NOT belong to this group. (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into their constituent digits. E.g. 13 – Operations on 13 such as adding/subtracting/multiplying to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)

Correct — B. Subtract inside each pair and compare the four gaps.

Rule for the group: second = first − 216, and 216 is 6 cubed.

335 − 119 = 216
317 − 101 = 216
308 − 92 = 216
358 − 152 = 206

The pair that breaks the shared gap is 358 - 152 → option (b)

Why the others are wrong

• (a)
  335 - 119 — 335 - 119 gaps by 216, the same as two other pairs, so it belongs to the group and cannot be the one that stands out.
• (c)
  317 - 101 — 317 - 101 gaps by 216 as well. The question asks for the pair that does not share the rule, not for one that does.
• (d)
  308 - 92 — 308 - 92 gaps by 216 too. Three pairs sharing this gap is exactly what makes them a group.

An odd-one-out on number pairs is a difference hunt. Compute all four gaps before judging any of them — the rule is whichever value appears three times.

If the differences do not settle it, move to ratios, then to squares and cubes. Here the first pass is enough.

The NOTE again bars digit-level work: 335 is a single number, not a 3, a 3 and a 5.

Key facts

• The three grouped pairs all satisfy second = first − 216.
• 358 − 152 = 206, ten short of 216.
• 216 = 6 × 6 × 6.

Common traps

• Checking two pairs, finding them equal, and stopping
• Subtracting in the wrong direction and comparing negative gaps carelessly
• Splitting 358 into 3, 5 and 8, which the NOTE forbids

No directly related past PYQ was found.