Memory number combination: add up to less than 20, forming 6 groups of numbers similar to telephone numbers for children to remember and remember.

Training purpose: to lay a solid foundation for calculation.

Training goal: add it within 20 minutes and blurt it out without thinking.

Training methods:

(1) Combine 6 numbers into a card the size of a poker;

(2) Before doing homework, read aloud for 5 times, and then recite it for 3 times;

(3) Keep practicing 1 week.

2. In addition to addition and subtraction? Round up? Law.

The essence of this method is addition and subtraction? Round up? After being converted into integers, it becomes easy to calculate.

For example:

For example, 97+ 14, here, for? Round up? We can make some changes by adding 97 to the integer 100. Then, this formula can evolve as follows: 97+14 =100-3+14 =100+(14-3).

Another example is 97- 18, right? Round up? We can also make some changes in the same way, 97-18 =100-3-18 =100-(18+3).

Round up? Method, a fast calculation method, is the most practical and commonly used method in primary school mathematics. Of course, this method is to be learned and used. For example: 399+99+498, why? Round up? And then what?

We can also change this formula to: 399+99+498 = 400-1+100-1+500-2, that is to say, do all three addends? Round up? Finally, after calculating 1000, subtract the extra 1+ 1+2.

3, step by step calculation

We use it? 25? 52? This calculation, the teacher can guide the students to calculate in three steps, starting with 5? What is the result of 52; And then calculate 20? What is the result of 52; Then add up the two results and you get 25? The calculation result of 52. Through step-by-step calculation, let students know what multiplication and division is, so as to improve their mathematical calculation ability.