1, which is the same as "rounding method" in integer operation. In decimal operation, four arithmetic laws and operation laws (such as commutative law, associative law and distributive law) are fully used to make partial sum, difference, product and quotient become integers and integer ten ... thus simplifying the operation.

2. In an expression with only addition and subtraction operations, add brackets to a part of the expression. If there is a plus sign in front of the brackets, the operation symbols in the brackets will not change; If there is a minus sign in front of the parentheses, the operation sign in the parentheses will change, that is, the plus sign will change to the minus sign, and the minus sign will change to the plus sign.

3. In the addition and subtraction formula with brackets, delete the brackets in the formula. If there is a plus sign in front of the bracket, the operation symbol in the bracket will remain unchanged after the bracket is removed; If there is a minus sign in front of the parentheses, the operation sign in the parentheses will change, that is, the plus sign will change to the minus sign, and the minus sign will change to the plus sign.

Extended data score calculation method:

1. When several products are added and subtracted, and there are the same factors in these products, we can use the method of extracting common factors to make clever calculations. If the addition and subtraction results of other factors in the product just add up to integer ten, integer hundred, integer thousand, integer ten thousand, or some relatively simple numbers, it will be more convenient to calculate. This method is called "extracting common factors".

2. When a group of fractions are mixed together, in order to "round up" or make up a simple number, it is often necessary to split the numerator or denominator in the fractions first, and then carry out grouping operation. This ingenious calculation method is called "split method", also called "decomposition grouping method".

3. In the fractional formula with more congruences, letters are used to represent part of the formula, which makes the operation more convenient. This is the algebraic method in the fractional formula.