In mathematics, the calculation order of elementary arithmetic is "multiply first, then divide, then add and subtract". If there are brackets, count them first. " In other words, multiply and divide first, then add and subtract. There are parentheses, so you need to calculate the operation in parentheses first. Consider an expression of 2+3×4. Multiply 3×4 to get the result 12, and then add 2+ 12 to get the final result 14. The choice of this operation order is to keep the consistency and accuracy of mathematical operations, so that the calculation results will not be different because of the different operation order.