SSC CGL 2024 Tier-I · 23 September 2024, Shift 3 · General Intelligence and Reasoning · Question 16 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 10 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? 6 × 3 + 8 ÷ 2 + 21 + 5 × 4 – 14 ÷ 7 = 53

(a)8 and 4
(b)3 and 5
(c)21 and 14
(d)2 and 4

Answer

Why

Correct — C. Work the printed line first, under BODMAS.

6 × 3 = 18, 8 ÷ 2 = 4, 5 × 4 = 20, 14 ÷ 7 = 2
18 + 4 + 21 + 20 − 2 = 61, against a target of 53 — you need 8 less.

Now interchange 21 and 14:
6 × 3 + 8 ÷ 2 + 14 + 5 × 4 − 21 ÷ 7
= 18 + 4 + 14 + 20 − 3
= 53

The added term drops by 7 and the subtracted term grows by 1, which is the 8 required — so option (c) is the swap.

Why the others are wrong

(a)
8 and 4 — Swapping 8 and 4 gives 18 + 2 + 21 + 40 − 2 = 79. Moving the 8 into a multiplication pushes the total up when it has to come down.
(b)
3 and 5 — Swapping 3 and 5 gives 30 + 4 + 21 + 12 − 2 = 65. That is 4 more than 61, and the equation needs 8 fewer.
(d)
2 and 4 — Swapping 2 and 4 gives 18 + 2 + 21 + 10 − 2 = 49. It overshoots — 12 comes off the total where only 8 was wanted.

Concept

These items reward BODMAS discipline more than cleverness.

Evaluate the printed equation first and record how far off it is. Here 61 against a target of 53, so the swap must remove exactly 8.

That number tells you where to look. Swapping two plain added terms changes nothing, while a swap that moves a number into a multiplication or division changes the total by an amount you can estimate, so the gap rules options out quickly.

The rider 'two numbers, not digits' means the whole numerals change places. You may exchange 21 with 14, never the 2 of 21 with the 1 of 14.

The pair you are hunting need not be two added numbers. Here 21 sits in an added term and 14 inside a division, so one swap moves the line in two places at once.

There is no shortcut on this page worth the risk. Work out the gap — 8 — then test the four pairs against it. Four short evaluations settle the question.

Key facts

As printed, 6 × 3 + 8 ÷ 2 + 21 + 5 × 4 − 14 ÷ 7 evaluates to 61.
After 21 and 14 change places the same line evaluates to 53.
Under BODMAS every multiplication and division is done before any addition or subtraction.
The rider 'not digits' means whole numerals are exchanged, never single digits inside them.

Study next

Sign-interchange questions, where + and − or × and ÷ swap meaningBODMAS on expressions that mix brackets with divisionBalancing an equation by testing each option rather than solving it

Common traps

Adding and subtracting from left to right and never reaching 61
Exchanging the digits of 21 and 14 instead of the whole numbers
Testing options at random instead of first working out the gap of 8

SSC prints one long mixed-operation line, gives a target value and asks which pair of whole numbers must change places. The same stem appears at 09 Sep 2024, 16:00, Reasoning Q.7 and at 10 Sep 2024, 12:30, Reasoning Q.10 and Q.20.

Related PYQs

No directly related past PYQ was found.

Topic: Numerical Operations — all 73 SSC CGL questions on it, every solved shift.