2023 CSAT, all questions

UPSC Prelims 2023 · CSAT

Question 9: Basic Numeracy

If ABC and DEF are both 3-digit numbers such that A, B, C, D, E and F are distinct non-zero digits such that ABC + DEF = 1111, then what is the value of A + B + C + D + E + F ?

a28
b29
c30
d31

AnswerUPSC’s answer is (d).

Add column by column. Units: C + F must end in 1, and since the digits are non-zero, C + F = 11 with carry 1. Tens: B + E + 1 ends in 1, so B + E = 10, carry 1. Hundreds: A + D + 1 = 11, so A + D = 10. Total = 10 + 10 + 11 = 31. Example: 124 + 987 = 1111, with all six digits distinct.

Why each option is right or wrong
  • (a) Wrong: the sum is always 31.
  • (b) Wrong: the sum is always 31.
  • (c) Wrong: the sum is always 31.
  • (d) Right: A + D = 10, B + E = 10, C + F = 11.

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

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Source: UPSC, Civil Services (Preliminary) Examination 2023, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.