Finding The Number of Digits (Tìm số chữ số)

Finding The Number of Digits

Tìm số chữ số

The Opening Problem

• How many digits are used for the page numbers in a book that has 150 pages?

• A book uses 312 digits altogether for its page numbers. How many page does the book have?

Example 1

How many digits are there from numbers 1 to 80?

Formula

 $Number\ of\ Digits\ of\ n-digits\ group=\ n\times Number\ of\ Terms$  

Multiple Choice

How many digits are there from numbers 1 to 60?

• 106

• 108

• 110

• 111

Multiple Choice

How many digits are there from numbers 1 to 120?

• 250

• 252

• 254

• 256

Multiple Choice

How many digits are there in a book that has 456 pages?

• 1260

• 1262

• 1264

• 1266

Example 2

A book uses 342 digits altogether for its page numbers. How many page does the book have?

Multiple Choice

71 digits are used to print the page numbers of a book. What is the last page number of the book?

• 30

• 40

• 50

• 60

Multiple Choice

222 digits are used to print the page numbers of a book. How many pages does the book have?

• 90

• 100

• 110

• 120

THANK YOU!