ORDER OF OPERATIONS - PEMDAS

If the expression consists of parenthesis, exponents, +, –, × and ÷, then the operations MUST be performed in the following order.

• Always work on the calculations within parenthesis first if any.
• Next, calculate the exponents.
• Then, carry out multiplication or division, working from left to right.
• Lastly, do addition or subtraction, working from left to right.

The order to perform combined operations is called the PEMDAS rule.

Note: A common mnemonic for PEMDAS is Please Excuse My Dear Aunt Sally.

Example:

Evaluate 10 ÷ 2 + 12 ÷ 2 × 3

Solution:

Using the PEMDAS rule, we need to evaluate the division and multiplication before subtraction and addition. It is recommended that you put in parenthesis to remind yourself the order of operation.

10 ÷ 2 + 12 ÷ 2 × 3

= ( 10 ÷ 2) + (12 ÷ 2 × 3)

= 5 + 18

= 23

The following videos show more examples of the application of PEMDAS:

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