Order of operations

(Redirected from PEMDAS)

The order of operations is a mathematical convention for arithmetic computation. The below list indicates the order to do arithmetic, from top to bottom.

• Parentheses -- when there are multiple operations and parentheses within the parentheses, treat the section inside as a separate expression and do the order of operations within said parentheses
• Exponents
• Multiplication and Division -- done from left to right
• Addition and Subtraction -- done from left to right

The order of operations is usually summarized by the acronym PEMDAS. An AoPS mnemonic you can use to remember the order of operations is "Please Evaluate, My Dear AoPS Students".

Sometimes, properties like the Communicative Property, Associative Property, and Distributive Property can be applied.

Examples

Example 1

Consider the expression $2^8-(3+5)$. First, we do addition first because it is in parentheses. $$2^8 - 8$$ Next, we evaluate $2^8$ because exponents go next. $$256-8$$ Afterward, there are no multiplication and division, so we can move on to addition and subtraction. $$248$$ Therefore, $2^8 - (3+5) = \boxed{248}$.

Example 2

Consider the expression $14(4\times 7-58)-1$. The operations in the parentheses go first, but there are subtraction and multiplication both involved. Within the parentheses, the multiplication goes first, then the subtraction. $$14(28 - 58) - 1$$ $$14(-30) - 1$$ Afterward, we do multiplication, then subtraction. $$-420-1$$ $$-421$$ Therefore, $14(4\times 7-58)-1 = \boxed{-421}$.