pemdas

Parenthesis, Exponents, Multiplication, Division, Addition, then Subtraction

• Changing the order of the addends does not change the sum. Changing the order of the factors does not change the product. Example: 15 + 9 = 9 + 15; 3 x 8 = 8 x 3.

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• The order of two numbers may be switched around and the answer is the same.

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• property (which applies both to multiplication and addition) by which numbers can be added or multiplied in any order and still yield the same value, e.g. (a + b) + c = a + (b + c) or (ab)c = a(bc)

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• In addition, adding 0 to a number leaves the number unchanged, or identical (2+0=2). In multiplication, the product of any number and 1 is that number (4X1=4). (See property of zero; property of one.)

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In mathematics, the additive inverse, or opposite, of a number a is the number that, when added to a, yields zero. The additive inverse of a is denoted by unary minus: −a. This can be seen as a shorthand for a common subtraction notation: