SSC CGL 2025 Tier-I · 14 September 2025, Shift 3 · General Intelligence and Reasoning · Question 17 of 95

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.

Identify the odd number: 1, 8, 27, 64, 121, 216

(a)64
(b)121
(c)216
(d)27

Answer

Why

Correct — B. Test each number against the cubes 1³, 2³, 3³ and so on.

Rule: the list is n³ for n = 1 to 6.

1 = 1³, 8 = 2³, 27 = 3³, 64 = 4³
Fifth place should be 5³ = 125, but the list has 121 = 11²
216 = 6³

121 is not a cube, so it is the odd number: option (b).

Why the others are wrong

(a)
64 — 64 = 4³, the fourth cube, in fourth place. It is also 8², but being a square as well does not break the cube pattern.
(c)
216 — 216 = 6³, the sixth cube, in sixth place, right after the slot where 125 belongs.
(d)
27 — 27 = 3³, the third cube, in third place. It is odd in the even/odd sense, but so are 1 and 121, so parity decides nothing.

Concept

An odd-number list is one family of numbers with one entry that breaks it. Name the family first: 1, 8, 27 and 64 are the first four cubes, and 216 is 6³.

Here the odd entry is a near miss: 121 sits 4 below 125, the cube that belongs in fifth place, and 121 is a square, 11².

'Odd' here means the entry that breaks the pattern. In the even/odd sense, 1, 27 and 121 are all odd, so that reading cannot pick one answer.

Key facts

The first six cubes are 1, 8, 27, 64, 125 and 216.
121 = 11², a square but not a cube.
64 = 8² = 4³, both a square and a cube, like 1.

Study next

Missing-number series built on squares, such as 1, 4, 9, 16, ?, 36Series built on n³ + 1 or n² − 1, where the family is shiftedNumbers that are both squares and cubes: 1, 64, 729

Common traps

Reading 'odd' as not even: 1, 27 and 121 are all odd numbers, so no single answer comes out.
Letting 121 pass as 125: the two differ by 4, and a quick eye slides past.

A squares series is asked at 14 Sep 2025, 09:00, Reasoning Q.18, where 1, 4, 9, 16, ?, 36 is completed by 25.

Related PYQs

No directly related past PYQ was found.

Topic: Semantic Classification — all 59 SSC CGL questions on it, every solved shift.