UPSC Prelims 2017·CSAT·Quantitative Aptitude·Number System

What is the total number of digits printed, if a book containing 150 pages is to numbered from 1 to 150?

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Last updated 23 May 2026, 3:31 pm IST
  1. A262
  2. B342Correct
  3. C360
  4. D450

Explanation

The total number of digits is calculated by summing the digits used for pages with 1, 2, and 3 digits. 1. Pages 1-9: There are 9 pages, each using 1 digit. Total = 9 * 1 = 9 digits. 2. Pages 10-99: There are (99 - 10 + 1) = 90 pages, each using 2 digits. Total = 90 * 2 = 180 digits. 3. Pages 100-150: There are (150 - 100 + 1) = 51 pages, each using 3 digits. Total = 51 * 3 = 153 digits. Adding these totals: 9 + 180 + 153 = 342 digits. Analyzing the options: A) 262 is incorrect. B) 342 is correct, matching our calculation. C) 360 is incorrect. D) 450 is incorrect. The final answer is B.
Quantitative Aptitude: What is the total number of digits printed, if a book containing 150 pages is to numbered from 1 to 150?
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