First of all, we must confirm the baby's math level, whether it will be simple addition and subtraction, and the most basic thing is addition within ten. Children must be taught not to be eager for success, but to pay attention to methods and step by step, so that children can learn well, learn quickly and understand thoroughly enough.

Carry plus digits, add single digits, add ten digits to one to ten digits, add ten digits, and add the obtained number to a ten to get the result. Ma Bao can explain this to her baby. This is a simple math problem.

The subtraction of natural numbers is not closed.

It is closed unless the minuend is greater than the minuend. For example, 1 1 cannot subtract 26. In this case, use one of two methods:

(1) says that 26 cannot be subtracted from 1 1;

(2) If the answer is an integer, it means a negative number, so the result of 1 1 minus 26 is-15.

The subtraction of real numbers is defined as the addition of signed numbers. Specifically, one number subtracts the negative number of another number. And then we have three? π= 3 +(? π)。 This helps to avoid introducing "new" operators such as subtraction, thus maintaining the "simplicity" of real numbers.