Addition and subtraction are the most basic operations in mathematics. In addition, two or more numerical values are added to get their sum. In subtraction, one value is subtracted from another to get their difference.

When calculating at the same level, it is calculated from left to right in turn. Two-stage operation, first multiply and then divide, then add and subtract. When there are brackets, count the inside of the brackets first, and then the outside of the brackets. When there are multiplication and addition and subtraction operations in the expression, the distribution law can be used to simplify the calculation.

When there are multiple brackets, count the brackets first, then the brackets, then the braces, and finally the brackets. If there is a power, calculate the power first. When performing mixed operations, the numbers in parentheses are calculated first, and the parentheses are from small to large. If there is a power, calculate the power first, and then from high to low.

In calculation, addition and subtraction can be used to solve various problems, such as calculating commodity prices and calculating time intervals. The concepts and operations of addition and subtraction are the most basic in mathematics and are often used in daily life.

Skills of addition and subtraction mixed operation;

1, the operation in parentheses comes first.

If there are parentheses in the expression, calculate the operation in parentheses first, and simplify the expression by using distribution law or association law as needed. Calculate from left to right in order, and calculate the addition and subtraction operations in the expression from left to right in operation order.

2. Merge similar projects

In the calculation process, merging similar items can simplify the expression. Similar terms refer to terms with the same variables, and their coefficients increase or decrease. Using inverse operation sometimes you can use inverse operation to simplify the calculation. For example, for a+b-c, it can be converted into addition operation by treating C as the inverse operation of-A-B.

3. Use the attribute of zero

In the process of operation, the expression can be simplified by using the property of zero. For example, a+0 = aa-0 = a-0 = a. Calculate from left to right. Calculate the addition and subtraction operations in the expression from left to right according to the operation order. Using these skills flexibly can simplify the process of adding and subtracting mixed operations and improve the calculation efficiency.