1, the number of digits of a natural number is called the number of digits. One digit is one digit, and two digits are two digits. . . . . . . The maximum digit is 9, the minimum digit is 1, the maximum digit is 99, and the minimum digit is 10.

2,0 cannot be called a single digit. There is a stipulation in the notation that the highest digit of a number cannot be 0.

The reason why there is such a regulation is that if there is no such regulation, 0 is a number, from which it can be concluded that the smallest two digits are 00 and the smallest three digits are 000, which is obviously wrong. Not only that, if there is no such regulation, it is impossible to determine how many digits a number is.

Extended data:

One digit is 123456789.

The two digits are101121416171819202/kloc. 04243444546474849505 15253545556575859606 16263646566676869707 17273747576777879808 18283848586878889909 19293949596979899?

The number of digits of a natural number is called the number of digits. The number of digits of a natural number is called the number of digits. One digit is one digit, two digits are two digits, three digits are three digits ... the number of n digits is n digits.