Question

The pages of a book are numbered from 1 to 100 manually . How many times will it be essential to write the number 5 ?

Answer 1

5 will be written 19 times as5,15,25,35,45,50,51,52,53,54,55,56,57,58,59,65,75,85,95

Answer 2

Given:

Page number 1 to 100

To Find:

The number of times the digit 5 needs to be written

Solution:

Find the number of 5s from page 1 to 49:

Number of 5s = 1 x 5

Number of 5s = 5

(i.e. 5, 15, 25, 35, 45)

Find the number of 5s from page 50 to 59:

Number of 5s = 1 x 9 + 1

Number of 5s = 10

(i,e, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59. Note that 55 has 2 5s)

Find the number of 5s from page 60 to 100:

Number of 5s = 1 x 4

Number of 5s = 4

(i.e. 65, 75, 85, 95)

Find the total number of 5s:

Total number of 5s = 5 + 10 + 4

Total number of 5s = 19

Answer: There are 19 5s from 1 to 100