SSC CGL 2024 Tier-I · 12 September 2024, Shift 2 · 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 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.

What will come in place of the question mark (?) in the following equation if ‘+’ and ‘−’ are interchanged and ‘×’ and ‘÷’ are interchanged? 16 ÷ 4 + 8 × 8 − 4 = ?

(a)67
(b)42
(c)11
(d)36

Answer

Why

Correct — A. Rewrite the line with the symbols swapped, then solve it normally.

Rule: swap first, then apply BODMAS to the new expression.

16 ÷ 4 + 8 × 8 − 4 becomes 16 × 4 − 8 ÷ 8 + 4
16 × 4 = 64
8 ÷ 8 = 1
64 − 1 + 4 = 67 → option (a)

Why the others are wrong

(b)
42 — 42 comes out of neither reading: the swapped line gives 67 under BODMAS and 11 worked strictly left to right. Check both and 42 appears in neither.
(c)
11 — 11 is the left-to-right answer: 16 × 4 = 64, then − 8 = 56, then ÷ 8 = 7, then + 4 = 11. Division still outranks subtraction after the swap.
(d)
36 — 36 matches neither the swapped line nor the printed one — leave the symbols alone and 16 ÷ 4 + 8 × 8 − 4 = 64, not 36.

Concept

Two things are being tested at once, and the second is the one that is easy to miss.

First, the substitution: every + becomes −, every − becomes +, every × becomes ÷, every ÷ becomes ×. Do it on paper, do not do it in your head as you evaluate.

Second, the order of operations. The swap changes the symbols, not the precedence rules. × and ÷ are still done before + and −, and the swap often moves a ÷ into a position that now has to be evaluated first.

There is nothing ambiguous here: the interchange is total and simultaneous, so a line with two + signs would get two − signs. The result 67 is a whole number, which is a useful sanity check on this format.

Key facts

The swapped expression is 16 × 4 − 8 ÷ 8 + 4.
Under BODMAS the two products are evaluated first: 16 × 4 = 64 and 8 ÷ 8 = 1.
64 − 1 + 4 = 67.
The same line worked left to right without BODMAS gives 11, which is why 11 is offered.

Study next

Symbol-interchange questions where only one pair is swappedBODMAS on expressions mixing division and subtraction, where left-to-right reading failsQuestions asking which pair of operations to interchange to make an equation true

Common traps

Evaluating left to right after swapping, which returns 11 here.
Swapping one pair and forgetting the other.
Swapping symbols while evaluating, so a symbol gets swapped twice or not at all.

SSC prints the swap instruction before the equation, so read to the end of the sentence before touching the arithmetic. The reverse form — which pair of operations must be interchanged to make the equation correct — is at Reasoning Q.13 of this 12 Sep 2024, 12:30 paper.

Related PYQs

No directly related past PYQ was found.