math review

Natural number

Positive counting numbers (1, 2, 3, …)

Whole number

Counting numbers plus 0

Rational number

A number that can be written as a fraction of integers

Irrational number

A number that cannot be written as a fraction

Real number

All rational and irrational numbers

Imaginary number

Numbers involving i √(negative), not on the real number line

Factor

A number that divides another number exactly

Prime number

A number >1 with only two factors: 1 and itself

Composite number

A number >1 with more than two factors

Commutative property

Order doesn’t change the result

Associative property

Grouping doesn’t change the result

Distributive property

Multiply a number by each term inside parentheses

Identity element

A value that keeps another value unchanged

Inverse element

A value that undoes another value, giving the identity

Scientific notation

Writing a number as (1–10) × 10ⁿ

Absolute value

A number’s distance from 0

Are rational numbers are closed under all four operations?

Yes (except for division)

Are real numbers closed under all four operations?

Yes

Are complex numbers closed under all four operations?

Yes

the sum of two irrational numbers is irrational? True or false

false

the sum of two irrational numbers irrational? True or false?

false, it isn’t always irrational. It can be rational depending on the numbers involved

Scientific notion

Represents numbers large or small in the for 𝑎×10𝑛

Positive x negative or negative x positive =

Negative

Ex: -8×4 =-32