19 19 good friend 1 9.
2828 hand in hand 2, 8.
Three, seven, three, seven, too close.
Four four six four six.
Five, five, five, five, five hands.
The method of filling ten is the basic idea of carry addition within 20. By using the method of filling ten, the carry addition within 20 can be transformed into the familiar problem of 10 plus several, which makes it difficult and easy.
Children should remember 9 to 1, 8 to 2, 7 to 3, 6 to 4 and 5 to 5.
Correlation principle
10 times 10 method is often used for addition within 20.
For example, calculate 9+6 = how much.
You can split 6 into "1" and "5", use 9+ 1 = 10, and then use 10 to add the remaining 5, that is, 10+5 = 15? .
You can decompose 9 into "5" and "4", use 4+6 = 10, and then use 10 to add the remaining 5, that is, 10+5 = 15? .
You can also split 9 into "4" and "5", or 6 into "5" and "1", where 5+5 = 10, the remaining 4+ 1 = 5, and then 10 plus 5, that is/kloc-.
Ten times ten is a simple operation when adding a number less than ten, such as 8+7 = 8+2+5 =10+5 =15.
Remember 1 and 9,2 and 8,3 and 7,4 and 6,5 and 5,
10 plus a few equals ten,
There is another way to break ten, which is the opposite of adding ten: for example,16-9 =10+6-9 =10-9+6 = 7.