SSC CGL 2024 Tier-I · 10 September 2024, Shift 2 · General Intelligence and Reasoning · Question 20 of 100

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 6 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

Which two numbers (not digits) should be interchanged to make the given equation correct? 72 – 6 + (18 ÷ 4) + 17 – (22 × 2) = 44

(a)22 and 18
(b)6 and 4
(c)6 and 22
(d)2 and 4

Answer

Why

Correct — B. Interchange 6 and 4, then work the line through under BODMAS.

Rule: make the swap first and evaluate afterwards — brackets and division before addition and subtraction, and equal-ranking signs from left to right.

After the swap the left side reads 72 – 4 + (18 ÷ 6) + 17 – (22 × 2).

Brackets: 18 ÷ 6 = 3 and 22 × 2 = 44

72 – 4 = 68
68 + 3 = 71
71 + 17 = 88
88 – 44 = 44 → option (b)

As printed, before any swap, the left side comes to 43.5, so something had to move.

Why the others are wrong

(a)
22 and 18 — Swapping them gives 72 – 6 + (22 ÷ 4) + 17 – (18 × 2), which is 66 + 5.5 + 17 – 36 = 52.5. It also leaves a fraction where the target is a whole 44.
(c)
6 and 22 — Swapping them gives 72 – 22 + (18 ÷ 4) + 17 – (6 × 2), which is 50 + 4.5 + 17 – 12 = 59.5, well past 44.
(d)
2 and 4 — Swapping them gives 72 – 6 + (18 ÷ 2) + 17 – (22 × 4), which is 66 + 9 + 17 – 88 = 4. Multiplying 22 by 4 swamps everything else on the line.

Concept

The instruction says numbers, not digits. Whole numbers move, so 18 may change places with 22, but you may not lift the 1 out of 18.

With only four candidate pairs on offer, substitution beats algebra: try each swap and stop at the one that balances.

Work brackets first, then read the remaining chain left to right. Addition and subtraction rank equally, so 72 – 4 + 3 is 71, not 72 – 7.

Only one of the four swaps clears the fraction created by 18 ÷ 4, which is a quick filter — but it is a filter, not a proof. Finish the arithmetic before marking.

Key facts

After swapping 6 and 4 the left side reads 72 – 4 + (18 ÷ 6) + 17 – (22 × 2) and equals 44.
As printed the left side equals 43.5, so the equation is false before any swap is made.
Addition and subtraction rank equally in BODMAS and are worked from left to right.
The question moves whole numbers, never individual digits.

Study next

Interchange questions in which two signs rather than two numbers must be swappedEquations where one sign and one number are exchanged togetherBODMAS chains containing nested brackets

Common traps

Swapping digits rather than whole numbers, which the question rules out in its own wording
Carrying out every addition before the subtractions instead of working left to right
Stopping at the first swap that clears the fraction without checking the final total

The rider — two numbers, not digits — is printed in the stem itself, so read it before you start swapping. The fastest route is then to substitute each option and stop at the one that balances.

This shift also asks an interchange item at Reasoning Q.10, and 11 Sep 2024, 09:00 opens with one at Reasoning Q.1.

Related PYQs

No directly related past PYQ was found.