Synopsis IAS

Answer

Solution

UPSC Prelims

Mathematics

Theme:

Number System / संख्या पद्धति

Q53 2019, Number System

A printer numbers the pages of a book starting with 1 and uses 3089 digits in all. How many pages does the book have?

• Digits required to print one digit numbers (1 to 9) = 9×1 = 9

• Digits required to print two digit numbers (10 to 99) = 90 × 2 = 180

• Digits required to print three digit numbers (100 to 999) = 900 × 3 = 2700.

• So, upto 999 pages we have 2700 + 180 + 9 = 2889 digits.

• Now from here onwards each number will use 4 digits and we are remaining with 3089 - 2889 = 200 digits.

• So 200/4 = 50 more numbers are there. i.e., 999 + 50 = 1049 pages in the book.

Q 53. 2019, Number System