Two sets of numbers are given below. In each set of numbers, certain mathematical operation(s) on the first number result(s) in the second number. Similarly, certain mathematical operation(s) on the second number result(s) in the third number and so on. Which of the given options follows the same set of operations as in the given sets? (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.) 48 – 50 – 46 – 52; 37 – 39 – 35 – 41

Correct — A. Read the operations off the two given chains before touching the options.

48 → 50 is +2, 50 → 46 is −4, 46 → 52 is +6.
37 → 39 is +2, 39 → 35 is −4, 35 → 41 is +6.

Rule: +2, then −4, then +6.

Apply it to option (a): 26 + 2 = 28, then 28 − 4 = 24, then 24 + 6 = 30.

That produces 26 – 28 – 24 – 30, which is option (a) exactly.

Why the others are wrong

• (b)
  21 – 23 – 29 – 27 — 21 + 2 = 23 is right, but the third term should be 23 − 4 = 19, not 29. This chain rises where the rule turns down.
• (c)
  19 – 17 – 21 – 25 — The first step is already wrong: 19 + 2 = 21, not 17. This chain opens by subtracting 2 instead of adding it.
• (d)
  15 – 13 – 9 – 19 — 15 + 2 = 17, not 13. This chain also opens with a subtraction, and its later steps do not recover the rule either.

These items give you two worked chains and ask which option runs on the same engine. The second chain is there so you can confirm the rule instead of guessing it from one example.

Work with the differences between consecutive terms, not the terms themselves. Both given chains produce +2, −4, +6 — an alternating pattern whose step sizes grow by 2 each time.

The note bars digit-splitting, so 48 stays forty-eight throughout. Every operation acts on the whole number.

Key facts

• 48 – 50 – 46 – 52 has differences of +2, −4, +6.
• 37 – 39 – 35 – 41 has the same differences, +2, −4, +6.
• Applying +2, −4, +6 to 26 gives 28, then 24, then 30.

Common traps

• Matching only the first difference and stopping, which leaves option (b) alive
• Reading 26 – 28 – 24 – 30 as a broken +2 series and rejecting it
• Breaking 48 into 4 and 8, which the question's note forbids

No directly related past PYQ was found.