SSC CGL 2025 Tier-I · 14 September 2025, Shift 2 · General Intelligence and Reasoning · Question 24 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.

If '+' means '×', '×' means '−', '−' means '÷', then 20 + 5 × 2 − 10 = ?

(a)89
(b)67
(c)78.89
(d)99.8

Answer

Why

Correct — D. Swap the signs first, then apply BODMAS.

Rule: + becomes ×, × becomes −, − becomes ÷.

20 + 5 × 2 − 10 becomes 20 × 5 − 2 ÷ 10

Multiply: 20 × 5 = 100
Divide: 2 ÷ 10 = 0.2
Subtract: 100 − 0.2 = 99.8

That is option (d).

Why the others are wrong

(a)
89 — 89 is a whole number, but the working takes 2 ÷ 10 = 0.2 away from 100, so the answer must end in .8.
(b)
67 — 67 is far below 100 − 0.2. Once + becomes ×, the expression starts from 20 × 5 = 100, and just 0.2 is subtracted.
(c)
78.89 — 78.89 has a .89 part that no step here produces. The one fraction in the working is 2 ÷ 10 = 0.2, and 100 − 0.2 = 99.8.

Concept

A sign-substitution item has two stages. First rewrite the expression with the new meanings, changing each sign once. Then evaluate it with BODMAS: division and multiplication before addition and subtraction.

Here the code turns 20 + 5 × 2 − 10 into 20 × 5 − 2 ÷ 10. The ÷ joins 2 and 10 before the subtraction happens, which is where the 0.2 comes from.

Working left to right after the swap gives (100 − 2) ÷ 10 = 9.8, which is not an option. That is the signal that the order of operations was skipped.

Key facts

After substitution, 20 + 5 × 2 − 10 reads 20 × 5 − 2 ÷ 10.
BODMAS does division and multiplication before subtraction.
20 × 5 − 2 ÷ 10 = 100 − 0.2 = 99.8.

Study next

Four-sign codes, where ÷ also changes meaningFinding which two signs must be interchanged to balance an equationSubstitution items with brackets, where the bracket is worked first

Common traps

Changing signs in a chain, so a + that became × is then turned into −.
Working left to right after substituting, which gives 9.8.

The same three-sign code returns at 17 Sep 2025, 16:00, Reasoning Q.23, where 10 − 5 + 3 × 2 becomes 10 ÷ 5 × 3 − 2 = 4.

19 Sep 2025, 09:00, Reasoning Q.23 uses a four-sign code on 20 + 5 × 4 − 2 and also ends in a decimal, 17.5.

Related PYQs

No directly related past PYQ was found.

Topic: Numerical Operations — all 92 SSC CGL questions on it, every solved shift.