SSC CGL 2025 Tier-I · 15 September 2025, Shift 2 · General Intelligence and Reasoning · Question 8 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

Complete the pattern: 2, 6, 14, 30, 62, ?

(a)126
(b)124
(c)130
(d)128

Answer

Why

Correct — A.
Rule: × 2 + 2 at every step.

2 × 2 + 2 = 6
6 × 2 + 2 = 14
14 × 2 + 2 = 30
30 × 2 + 2 = 62

Next: 62 × 2 + 2 = 126 → option (a).

Check: the gaps 4, 8, 16, 32 double, so the next gap is 64, and 62 + 64 = 126.

Why the others are wrong

(b)
124 — 124 is 62 × 2 with the + 2 left off. Every earlier step adds 2 after doubling, so the last one must too.
(c)
130 — 130 needs a gap of 68 after 62. The gaps run 4, 8, 16, 32, so the next one is 64, not 68.
(d)
128 — 128 is 2⁷, a clean power of two. Each term sits 2 below a power of two (4 − 2, 8 − 2, 16 − 2), so the next is 128 − 2.

Concept

When a series roughly doubles, test × 2 + k for a small k. Here k = 2 fits every step from 2 to 62.

Two other readings agree. The gaps 4, 8, 16, 32 double each time. And each term is 2 less than a power of two, 2ⁿ⁺¹ − 2. All three point to 126.

124 and 128 sit on either side of the answer, one from dropping the + 2 and one from stopping at the power of two, so a rough estimate cannot separate them.

Key facts

× 2 + 2 from 2 gives 2, 6, 14, 30, 62, 126.
Each term equals 2ⁿ⁺¹ − 2 for n = 1, 2, 3 …
When the gaps double, the next gap is twice the last: 32 × 2 = 64.

Study next

× 2 + 1 and × 2 − 1 seriesSeries with a growing multiplier, such as × 2 + 1, × 3 + 1, × 4 + 1Series whose gaps form their own pattern

Common traps

Doubling 62 and forgetting the + 2, which gives 124
Stopping at the power of two, 128

17 Sep 2025, 16:00, Reasoning Q.24 uses × 2 + 1 instead: 3, 7, 15, 31, 63, ? is keyed 127.

13 Sep 2024, 12:30, Reasoning Q.8 uses × 2 − 1: 9 17 33 65 129 ? is keyed 257.

Related PYQs

No directly related past PYQ was found.

Topic: Number Series — all 112 SSC CGL questions on it, every solved shift.