SSC CGL 2025 Tier-I · 21 September 2025, Shift 1 · General Intelligence and Reasoning · Question 15 of 99

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 13 September 2026.

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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.

If 2 = 12 3 = 36 4=80 5=150 6=252 7=392 Then 8 = ?

(a)576
(b)625
(c)484
(d)925

Answer

Why

Correct — A.
Rule: n → n³ + n², the same as n² × (n + 1).

Check: 2 → 8 + 4 = 12
3 → 27 + 9 = 36
6 → 216 + 36 = 252
7 → 343 + 49 = 392

Apply to 8:
8³ + 8² = 512 + 64
= 576 → option (a).

Why the others are wrong

(b)
625 — 625 is 25², not 8³ + 8². The rule gives 512 + 64 = 576, and 625 would need the jump from 392 to be 233 instead of 184.
(c)
484 — 484 is only 92 above 392, but the previous jump was 140 (252 → 392). The jumps grow every step, so the next term must lie above 532.
(d)
925 — 925 needs a jump of 533 from 392. The jumps run 24, 44, 70, 102, 140, so the next is 184, and 392 + 184 = 576.

Concept

A number-mapping puzzle hides a formula that turns each left number into its right number. Test powers of n first: each value sits just above n³ (8, 27, 64 …), and the leftover is exactly n² (4, 9, 16 …).

Factorised, n³ + n² = n² × (n + 1): 2² × 3 = 12, 3² × 4 = 36.

A second check needs no formula. The jumps 24, 44, 70, 102, 140 grow by 20, 26, 32, 38, steps of 6, so the next jump is 184 and 392 + 184 = 576.

Three options are perfect squares (576 = 24², 625 = 25², 484 = 22²), so 'it looks like a square' decides nothing here. Only the rule separates them.

Key facts

n³ + n² = n² × (n + 1), so for n = 8 the value is 64 × 9 = 576.
Cubes to learn: 2³ = 8, 3³ = 27, 4³ = 64, 5³ = 125, 6³ = 216, 7³ = 343, 8³ = 512.
The jumps 24, 44, 70, 102, 140 have second differences 20, 26, 32, 38, rising by 6.

Study next

Number mappings built on n² + n or n³ − nSecond and third differences as a check on cubic seriesThe same values written as a series instead of pairs

Common traps

Hunting for one fixed multiplier: here the multiplier of n² changes with n (3, 4, 5 …).
Picking 625 or 484 because they are perfect squares near the answer.

The same values appear as a plain series at 16 Sep 2025, 16:00, Reasoning Q.6: 2, 12, 36, 80, 150, ? is keyed 252, which is 6² × 7, the n² × (n + 1) rule starting from n = 1.

Related PYQs

No directly related past PYQ was found.

Topic: Symbolic/Number Analogy — all 210 SSC CGL questions on it, every solved shift.