Carry addition has a formula: add the same digits, starting with single digits; Don't worry if you pass ten, try to get one from ten. Preschool children learn to calculate, which lies in enlightenment, mainly to make children interested in calculation, activate their minds and develop their thinking, rather than learning more and deeper, so don't pursue the difficulty of calculation.

According to children's possibilities and needs, children learn mathematics in different ways. If children have the possibility and need to learn, they should be taught. If children have difficulties and antipathy, don't impose them.

The way to learn the advance and retreat operation is to practice the operation within 10, which is the basis of carry abdication operation. The operation within 10 is easy to make clear, otherwise the operation after 10 will be very chaotic.