2015 CSAT, all questions

UPSC Prelims 2015 · CSAT

Question 57: Basic Numeracy

If ABC × DEED = ABCABC; where A, B, C, D and E are different digits, what are the values of D and E ?

aD = 2, E = 0
bD = 0, E = 1
cD = 1, E = 0
dD = 1, E = 2

AnswerUPSC’s answer is (c).

The six-digit number ABCABC equals ABC × 1001, because repeating a three-digit number multiplies it by 1001. So DEED must equal 1001, giving D = 1 and E = 0. Check with ABC = 123: 123 × 1001 = 123123. D and E are different from each other, and A, B and C can be chosen different from them.

Why each option is right or wrong
  • (a) Wrong: D = 2, E = 0 gives DEED = 2002, not 1001.
  • (b) Wrong: D = 0, E = 1 gives 0110, not a four-digit number, and not 1001.
  • (c) Right: DEED = 1001.
  • (d) Wrong: D = 1, E = 2 gives 1221, not 1001.

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

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Source: UPSC, Civil Services (Preliminary) Examination 2015, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.