Because the highest digit in the integer range cannot be 0, it is pointed out that 0 is not a number, and it is generally not said that 0 is a number, according to the contents of Book 8 for Mathematics Teachers in Nine-year Compulsory Education for Six-year Primary Schools. Integers are divided into negative numbers and non-negative numbers. The smallest number in the non-negative range is 1, while the smallest number in the integer range is -9. The minimum digit is 1, the maximum digit is 99, and the minimum digit is 10.

Numbers written with numbers other than 0 are called one digit. For example: 1, 3, 9. A number represented by two numbers, in which the leftmost number is not 0, is called a two-digit number. For example:10,29,87. A number represented by three numbers, in which the leftmost number is not 0, is called a three-digit number. For example:100,290,607. Therefore, in a number, what is the number of numbers? This number is called several digits.