6.5.1 Numerical Expressions

Definitions:

• • Numerical Expressions --> A combination of numbers and operations

  • Order of Operations --> Tells you which operation to perform next

    • You might have heard of the phrase PEMDAS, or  Please Excuse My Dear Aunt Sally which means:

      • Parenthesis 

      • Exponents

      • Multiply or Divide (From left to right)

      • Add or Subtract (From left to right)

Notice in the first example that the multiplication is done BEFORE the addition. This is because in PEMDAS, multiplication comes before addition, therefore, it must be done first. 

In the second example, it has subtraction and addition. Addition does come before subtraction in PEMDAS, but you will notice above that it says add or subtract from left to right. Since subtraction is the leftmost operation, we must do it before the addition. If the signs were reversed, then we would add first, then subtract.