Carry-up addition within 20: Method 1: "Ten-up method" (key points: look at large numbers, divide them into decimals, make up ten, and add the remainder) 8+5 = 8+2+3 =13; Method 2: "Five to five is ten" (applicable when both addends are greater than or close to 5) 6+7 = 5+5+1+2 =13; Method 3: "Add, subtract and supplement more" 8+5= 10+5-2= 13.

Carry addition in 20:

"Add to ten", "Add to decimal, divide by large number", add the decimal to 10, and then calculate.

For example: 3+9(3+7= 10, 9 can be divided into 7 and 2, 10+2 = 12).

"Round up a large number and divide it into decimals", make a large number 10, and then calculate.

For example: 8+7(8+2= 10, 7 can be divided into 2 and 5, 10+5 = 15).

Integer addition calculation rules:

The same numbers are aligned from the low order. When the numbers add up to ten, they will advance to the previous number.

Calculation rules of integer subtraction:

The same numbers are aligned from the lower number. If the number of digits in the digit is not reduced enough, it will be reduced from the previous digit to make up ten digits, and then combined with the number of digits in the standard.