1, calculate n plus 1. Any child who can count in turn and understand that it means to increase 1 can easily learn to calculate n plus 1, including 10 plus 1, 20 plus 1, 99 plus 65438+.

2. Calculate N minus 1. Any child who can count backwards and understand the meaning of minus 1 can learn to calculate N minus 1, including 1 1 minus 1, 2 1 minus 1 and/kloc-0.

3. Add and subtract integers 10, such as 10 plus 10, 20 plus 10, ... 90 plus 10. Children who can count each 10 and understand that it means increasing or decreasing 10 in turn are easy to learn.

4. Addition and subtraction of integer 5, such as 0 plus 5, 5 plus 5, 10 plus 5, or even 95 plus 5, is not difficult for children who can count every 5, and it is understandable that it means addition and subtraction of 5.

5. Calculate 10 plus n, including 10 plus 1, 10 plus 2... 10 plus 9. Once children understand that 10 plus a few equals more than ten, they can not only quickly calculate 10 plus n, but also generalize it to 20 plus n.