Similar subtraction:
The same subtraction is a simple and quick addition. For example, to calculate 6+3, we can first find the nearest decimal number 10, and then add the remaining 3 through 10-6=4 to get 6+3 =10+(-4)+3 = 9+3 =12.
Appendix segmentation method:
Appendix splitting refers to splitting an addend into numbers that are easier to calculate. For example, to calculate 8+7, you can divide 7 into 5 and 2, and then add them to 8 respectively, that is, 8+7 = 8+5+2 =13+2 =15.
Carry addition:
Carry addition applies to the addition of two numbers, and the sum of one bit is greater than 9. For example, if you calculate 9+7, you need to carry it because the sum of single digits is greater than 9, and the result is 10+6= 16.
Borrowing subtraction:
Borrowing subtraction is suitable for the case that when two numbers are subtracted, the subtracted bit is not enough. For example, if you calculate 9-5, you need to borrow from ten digits because there are not enough single digits, and the result is 8+ 10-5= 13.
The role of zero:
In addition and subtraction, any number adds or subtracts zero, and the result is the number itself. For example, 5+0=5 and 7-0=7.
Carry subtraction:
When the single digits are not enough, you can borrow from the high position and then subtract. For example, after calculating 18-9, it is necessary to borrow from ten digits because the single digits are not reduced enough, and the result is 17-9=8.
Decimal subtraction:
Ten-digit subtraction refers to the subtraction operation starting from ten digits. For example, to calculate 34- 17, first borrow from the ten digits, and the result is 24-7= 17, and then subtract the single digits, and the result is 17.
Carry rule:
For some specific number combinations, we can remember their carry rules to simplify the calculation. For example, 9+6 is single digit 5, decimal digit 1, and the result is 15.
Conversion sequence method:
The transformation order method is suitable for adding or subtracting two numbers, one is larger and the other is smaller. For example, if you calculate 7+9, you can change the order to 9+7 and get the result of 16.
Definition law:
According to the mathematical definition, the sum of any number and zero equals the number itself, and the difference between any number and itself equals zero. Therefore, the definition law can be used to simplify the calculation in addition and subtraction.