Basic Math and Pre-Algebra Workbook For Dummies, 2nd Edition

Chapter 4

It's Just an Expression

In This Chapter

Evaluating Big Four expressions

Knowing how to evaluate powers

Putting parentheses into the mix

Getting clear on the order of operations

An arithmetic expression is any string of numbers and operators that can be calculated. In some cases, the calculation is easy. For example, you can calculate 2 + 2 in your head to come up with the answer 4. As expressions become longer, however, the calculation becomes more difficult. You may have to spend more time with the expression 2 × 6 + 23 – 10 + 13 to find the correct answer of 38.

The word evaluate comes from the word value. When you evaluate an expression, you turn it from a string of mathematical symbols into a single value — that is, you turn it into one number. But as expressions get more complicated, the potential for confusion arises. For example, think about the expression 3 + 2 × 4. If you add the first two numbers and then multiply, your answer is 20. But if you multiply the last two numbers and then add, your answer is 11.

To solve this problem, mathematicians have agreed on ...