1. signed shift method: when a calculation problem has only one-level operation (only multiplication and division or only addition and subtraction) and no brackets, we can "sign shift". For example: 23-11+7 = 23+7-11.

2. Combination method: bracket method:

(1) When adding parentheses for addition and subtraction, there is a plus sign in front of the parentheses, a constant sign in the parentheses, a minus sign in front of the parentheses and a sign in the parentheses. For example: 23+ 19-9=23+( 19-9).

(2) When the multiplication and division method is bracketed, the multiplication symbol is in front of the bracket, the constant symbol is in the bracket, the division symbol is in front of the bracket, and the symbol is changed in the bracket. For example: 2×6÷3=2×(6÷3)

3. Combination method: bracket removal method:

(1) In addition and subtraction, when the brackets are removed, a plus sign is added before the brackets and a minus sign is added before the brackets. When the brackets are deleted, the symbol will change (the original addition in brackets is now reduced; It used to be negative, but now it will be positive. For example:17+(13-7) =17+13-7.

(2) When the brackets are removed in the multiplication and division method, the brackets are preceded by a multiplication sign, followed by a constant sign, followed by a division sign, and followed by a change sign. For example: 1×(6÷2)= 1×6÷2.

4. Law of multiplication and distribution:

(1) is an addition or subtraction operation in brackets. Multiply by another number and pay attention to the distribution. For example: 8× (5+11) = 8× 5+8×11.

(2) Common factor extraction method. For example: 9×8+9×2=9×(8+2).