Following the Order of Operations
Part of the Basic Math & Pre-Algebra For Dummies Cheat Sheet
When arithmetic expressions get complex, use the order of operations (also called the order of precedence) to simplify them. Complex math problems require you to perform a combination of operations — addition, subtraction, multiplication, and division — to find the solution. The order of operations simply tells you what operations to do first, second, third, and so on.
Evaluate arithmetic expressions from left to right, according to the following order of precedence:
Multiplication and division
Addition and subtraction
Following the order of operation is important; otherwise, you'll end up with the wrong answer. Suppose you have the problem 9 + 5 × 7. If you follow the order of operations, you see that the answer is 44. If you ignore the order of operations and just work left to right, you get a completely different — and wrong — answer:
9 + 5 × 7 = 9 + 35 = 44 RIGHT
9 + 5 × 7 = 14 × 7 = 98 WRONG!