What are the calculation methods of addition and subtraction within 100?

The addition and subtraction methods within 100 are as follows:

1, add to ten method: first decompose the number, and then add it to whole ten or whole hundred.

For example: 2 1+26, you can divide 2 1 into 17+4, 4 and 26 to form an integer 30, that is, 17+4+26=47.

2. Decomposition method: according to certain requirements, the number is decomposed into several arrays, which is convenient for calculation.

For example, 15 can be decomposed into three 5s; 24 can be broken down into 20 plus 4.

3. Story-making method: suppose some situations, put boring numbers into situations, and connect with specific things for easy understanding and calculation.

For example, when the bus leaves from the station, there are 18 passengers on board. At the next stop, 12 passengers get on and 6 passengers get off. How many passengers are there on the plane? ( 18+ 12-6=24)。