2024 CSAT, all questions
UPSC Prelims 2024 · CSAT
Question 48: Basic Numeracy
If the sum of the two-digit numbers AB and CD is the three-digit number 1CE, where the letters A, B, C, D, E denote distinct digits, then what is the value of A?
a9
b8
c7
dCannot be determined due to insufficient data
AnswerUPSC’s answer is (a).
AB + CD = 1CE gives 10A + B + 10C + D = 100 + 10C + E, so 10A + B + D = 100 + E. For distinct digits B + D is at most 17, so 10A must be at least 83, making A = 9. (A = 8 would need B + D to be at least 20, which is impossible.) Example: 97 + 28 = 125 fits all conditions. So A = 9.
Why each option is right or wrong
- (a) Right. A = 8 would need B + D of at least 20, which is impossible, so A = 9.
- (b) Wrong. With A = 8, B + D would have to be at least 20.
- (c) Wrong. With A = 7, B + D would have to be at least 30.
- (d) Wrong. The value of A is forced to be 9.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2024, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.