UPSC Prelims 2007 · General Studies

Question 146: Basic Numeracy

If all the numbers from 501 to 700 are written, what is the total number of times the digit 6 appears?

a138

b139

c140

d141

AnswerThe answer is (c).

Count the digit 6 by place from 501 to 700. Units place: 506, 516, ..., 696 gives 20 numbers. Tens place: 560-569 and 660-669 gives 20. Hundreds place: 600-699 gives 100, and 700 has no 6. Total 20 + 20 + 100 = 140.

Why each option is right or wrong

(a) 138 undercounts by 2.
(b) 139 undercounts by 1.
(c) Correct: 20 + 20 + 100 = 140.
(d) 141 overcounts by 1.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2007, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.