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Lesson 3: Irrational numbers

# Classifying numbers review

Review whole numbers, integers, rational, and irrational numbers.  Then, practice identifying each.

## Whole numbers

start color #1fab54, start text, W, h, o, l, e, space, n, u, m, b, e, r, s, end text, end color #1fab54 are numbers that do not need to be represented with a fraction or decimal. Also, whole numbers cannot be negative. In other words, whole numbers are the counting numbers and zero.
Examples of whole numbers:
4, comma, 952, comma, 0, comma, 73

## Integers

start color #11accd, start text, I, n, t, e, g, e, r, s, end text, end color #11accd are whole numbers and their opposites. Therefore, integers can be negative.
Examples of integers:
12, comma, 0, comma, minus, 9, comma, minus, 810

## Rational numbers

start color #7854ab, start text, R, a, t, i, o, n, a, l, space, n, u, m, b, e, r, s, end text, end color #7854ab are numbers that can be expressed as a fraction of two integers.
Examples of rational numbers:
44, comma, 0, point, start overline, 12, end overline, comma, minus, start fraction, 18, divided by, 5, end fraction, comma, square root of, 36, end square root

## Irrational numbers

start color #ca337c, start text, I, r, r, a, t, i, o, n, a, l, space, n, u, m, b, e, r, s, end text, end color #ca337c are numbers that cannot be expressed as a fraction of two integers.
Examples of irrational numbers:
minus, 4, pi, comma, square root of, 3, end square root

## How are the types of number related?

The following diagram shows that all whole numbers are integers, and all integers are rational numbers. Numbers that are not rational are called irrational.