Question

The pages in Nisha s book are numbered from 1.She found that total number of 501 digids are used to write all the page numbers.For example 2 digids for page number 23 and 3 digids for page number 101.How manny pages does the book have?

Answer 1

There are 9 one-digit pages (1 - 9) → 9(1)

There are 90 two-digit pages (10 - 99) → 90(2)

There are "x" three-digit pages (100 - ???) → x(3)

9(1) + 90(2) + x(3) = 501

9 + 180 + 3x = 501

189 + 3x = 501

3x = 312

x = 104

Answer: 104 pages