The same operation(s) are followed in all the given number pairs except one. Find that odd number pair. (NOTE : Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 – Operations on 13 such as adding /deleting /multiplying etc., 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 — C. Test one operation across all four pairs before deciding which breaks.

Rule: the second number is the first multiplied by 13.

Option (a): 11 × 13 = 143, and 143 is printed.
Option (b): 13 × 13 = 169, and 169 is printed.
Option (d): 15 × 13 = 195, and 195 is printed.

Option (c) needs 12 × 13 = 156, but the paper prints 152. That four-short pair is the odd one.

Why the others are wrong

• (a)
  11 : 143 — 11 × 13 = 143. Option (a) follows the shared rule exactly, so it cannot be the odd pair — the question wants the pair that breaks the operation, not the one that looks unusual.
• (b)
  13 : 169 — 13 × 13 = 169. Option (b) follows the rule. It tempts because 169 is a perfect square, but squaring is not the shared operation — it only coincides here because the first number happens to be 13.
• (d)
  15 : 195 — 15 × 13 = 195. Option (d) follows the rule. The bigger numbers make it feel like the outlier, but size is not the test — consistency with the shared operation is.

Odd-one-out number pairs are solved by finding the rule that fits three of the four, not by finding something odd about one of them.

Work the simplest relations in a fixed order: a constant difference, a constant ratio, a square or cube, then n × (n + k). Here the constant ratio wins, because three pairs are the first number times 13.

The printed NOTE matters. It bars breaking a number into its digits, which rules out reading 143 as 1, 4 and 3, and keeps the search on whole-number arithmetic.

Key facts

• 143 = 11 × 13, 169 = 13 × 13 and 195 = 15 × 13.
• 12 × 13 = 156, so the printed 152 falls short by 4.
• The item's NOTE forbids splitting a number into its digits, so every operation acts on the whole number.

Common traps

• Testing a rule against a single pair and stopping as soon as it fits.
• Reading 169 as a perfect square and building a squares rule that then fails on 143 and 195.
• Missing a four-unit shortfall because 152 and 156 look alike at a glance.

No directly related past PYQ was found.