This question should be taught with one digit and ten digits first: the first digit from the left is one digit and the second digit is ten digits. Several ones: several numbers are several 1, for example, there are five ones in 5, and five ones make up 5. There are eight ones in eight, and eight ones make eight.

How many tens are there in ten places, such as:

10 is 1, which means one 1 ten, and 20 is two or two tens.

There are dozens of 1: for example, the number 15, and the tenth place is 1, which means 1.

Ten, five is five, which means five ones.

15 has 1 tens and 5 ones.