2019 CSAT, all questions

UPSC Prelims 2019 · CSAT

Question 74: Basic Numeracy

If $ means 'divided by'; @ means 'multiplied by'; # means 'minus', then the value of 10#5@1$5 is

a0
b1
c2
d9

AnswerUPSC’s answer is (d).

Replace the symbols: 10 # 5 @ 1 $ 5 becomes 10 - 5 × 1 ÷ 5. By BODMAS, multiplication and division come before subtraction and go left to right: 5 × 1 = 5, then 5 ÷ 5 = 1. So 10 - 1 = 9. Doing the subtraction first, (10 - 5) × 1 ÷ 5 = 1, is the trap.

Why each option is right or wrong
  • (a) Wrong: no order of operations gives 0.
  • (b) Wrong: 1 comes from subtracting first, against BODMAS.
  • (c) Wrong: no order of operations gives 2.
  • (d) Right: 10 - 1 = 9.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

Practise this paper timedPrevious questionNext question

Source: UPSC, Civil Services (Preliminary) Examination 2019, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.