What can be the sum of the digits of a two-digit number? Three-digit? K-digit?

The sum of digits for a two-digit number can be from 1 to 18, for a three-digit number – from 1 to 21, for a K-digit – from 1 to 9 * K.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.