2023 CSAT, all questions
UPSC Prelims 2023 · CSAT
Question 16: Basic Numeracy
A 3-digit number ABC, on multiplication with D gives 37DD where A, B, C and D are different non-zero digits. What is the value of A + B + C ?
a18
b16
c15
dCannot be determined due to insufficient data
AnswerUPSC’s answer is (a).
Since ABC x D = 3700 + 11D, D must divide 3700 = 2^2 x 5^2 x 37. D is a digit, so D = 1, 2, 4 or 5. D = 1 gives a 4-digit ABC (3711) and D = 2 gives 3722/2 = 1861, also not 3 digits. D = 5 gives 751, but 5 repeats. D = 4 gives 3744/4 = 936, with all digits distinct. A + B + C = 9 + 3 + 6 = 18.
Why each option is right or wrong
- (a) Right: ABC = 936 and 9 + 3 + 6 = 18.
- (b) Wrong: the digits of 936 add to 18, not 16.
- (c) Wrong: the digits of 936 add to 18, not 15.
- (d) Wrong: the conditions fix ABC = 936 uniquely.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2023, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.