Area of a triangle
1/2 base x height

Area of a circle
Pi x radius squared

Circumference of a circle
pi x diameter

Pythagorean theorem
a^2 + b^2 = c^2 (c is hypotenuse)

whole number
a nonnegative number that is not expressed as a fraction or a decimal

Integer
a whole number or its opposite (number line)

Composite number
a number that has more than two factors

Order of operations
Parentheses, Exponents, Multiply/Divide, Add/Subtract (Please Excuse My Dear Aunt Sally)

Commutative Property
5 x 2 = 2 x 5
(5) (a) = (a) (5)
b + 3 = 3 + b

Associative Property
If parentheses can be moved to group different numbers in an arithmetic problem without changing the result, then the operation is associative. Addition and multiplication are associative.
2 + (3 + 4) = (2 + 3) + 4
2 (ab) = (2a) b

Distributive Property
5a + 5b = 5(a + b)
5(100 - 6) = (5 x 100) - (5 x 6)

Additive identity
The value that, when added to a number, does not change the number. For all integers, the additive identity is 0.
5 + 0 = 5

Multiplicative identity
The value that, when multiplied by a number, does not change the number. For all integers, the multiplicative identity is 1.
5 x 1 = 5

Multiplicative inverse
The number that, when multiplied by the number, gives you the multiplicative identity (1).
1/5 is the multiplicative identity of 5

Additive inverse
The number that, when added to the number, give you the additive identity (0).
The additive inverse of 3 is -3

Combination
Order does NOT matter

Permutation
Order does matter

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