You can teach children to keep large numbers in mind, and then put out decimal numbers by hand and count them. There are only a few ways. It is important for children to practice more and establish such a reaction, and children will naturally get started.
For example: 5+8=? You should put the big number 8 in your heart, put the decimal number 5 in by hand, and then count the numbers 5,9, 10,1,12, 13 with the big number 8 in your heart. This problem is equal to 13.