Math Elementary arithmetic The Calculations' Order

The Calculations' Order (PEMDAS)

PEMDAS is an acronym for the words:

  1. Parentheses
  2. Exponents
  3. Multiplication

    Division

  4. Addition

    Subtraction

It refers to the order in which these calculations need to be performed.

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Info

  • Parentheses need to be calculated before Exponents.
  • Exponents need to be calculated before Multiplication and Division.
  • Multiplication and Division need to be calculated in the order they occur from left to right.
  • Multiplication and Division need to be calculated before Addition and Subtraction.
  • Addition and Subtraction need to be calculated in the order they occur from left to right.

Examples 1

  1. $4\cdot5+2=?$

    calculations' order:

    • Multiplication before Addition

    $4\cdot5+2$ $=20+2$ $=22$

  2. $14-9+6=?$

    calculations' order:

    • Addition and Subtraction in the order they occur

    $14-9+6$ $=5+6$ $=11$

  3. $9\div3\cdot2=?$

    calculations' order:

    • Multiplication and Division in the order they occur

    $9\div3\cdot2$ $=3\cdot2$ $=6$

  4. $12-8\cdot5\div4+7=?$

    calculations' order:

    • Multiplication and Division before Addition and Subtraction
    • Multiplication and Division in the order they occur
    • Addition and Subtraction in the order they occur

    $12-8\cdot5\div4+7$ $=12-40\div4+7$ $=12-10+7$ $=2+7$ $=9$

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Remember

If there are parentheses in the calculation, the same PEMDAS rule applies to the calculation inside these parentheses.

Examples 2

  1. $(24\div4-8)\cdot7=?$

    calculations' order:

    • Parentheses before Multiplication and Division
    • Multiplication and Division before Subtraction

    $(24\div4-8)\cdot7$ $=(6-8)\cdot7$ $=-2\cdot7$ $=-14$

  2. $(5+4)\cdot2^{3}=?$

    calculations' order:

    • Parentheses before Exponents
    • Exponents before Multiplication

    $(5+4)\cdot2^{3}$ $=9\cdot2^{3}$ $=9\cdot8$ $=72$

  3. $14-(3+16\div4)\cdot2=?$

    calculations' order:

    • Parentheses before Multiplication and Division
    • Multiplication and Division before Addition and Subtraction

    $14-(3+16\div4)\cdot2$ $=14-(3+4)\cdot2$ $=14-7\cdot2$ $=14-14$ $=0$

  4. $6\cdot(20\div2-7)+4^{2}=?$

    calculations' order:

    • Parentheses before Exponents
    • Exponents before Multiplication and Division
    • Multiplication and Division before Addition and Subtraction

    $6\cdot(20\div2-7)+4^{2}$ $=6\cdot(10-7)+4^{2}$ $=6\cdot3+4^{2}$ $=6\cdot3+16$ $=18+16$ $=34$

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Hint

The acronym PEMDAS can be memorized through the phrase:

Please Excuse My Dear Aunt Sally.

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Info

In the UK they use the acronym BODMAS, which stands for:

  1. Brackets
  2. Orders
  3. Divide

    Multiply

  4. Add

    Subtract

and in Canada they use the acronym BEDMAS, which stands for:

  1. Brackets
  2. Exponents
  3. Divide

    Multiply

  4. Add

    Subtract

However, they all mean the same thing.