Question

How do you do number 25? At the bottom.

Answer 1

Answer-

The printer used 642 digits to print all the pages in the book.

Solution-

There are 250 pages numbered starting from 1 to 250.

The total number of digits would be the sum of digits of all single digits from 1 to 9, all double digits number from 10 to 99, and all triple digits number from 100 to 250.

There are 9 single digit numbers from 0 to 9, 90 double digit numbers from 10 to 99, and 151 triple digit numbers from 100 to 250.

So,

$\text{Total digits}=(1\times 9)+(2\times 90)+(3\times 151)\\\\=9+180+453\\\\=642$

Therefore, the printer used 642 digits to print all the pages in the book.