Math - Numbers

The Numbers

A number is a mathematical object used to count, meansure and label.

• 0 - Zero
• 1 - One
• 2 - Two
• 3 - Three
• 4 - Four
• 5 - Five
• 6 - Six
• 7 - Seven
• 8 - Eight
• 9 - Nine

Types of Numbers

• Natural($\N$): All the whole numbers from one to infinity.
• Integer($\Z$): All the whole numbers that can be positive, negative or zero.
• Rational($\mathbb{Q}$): All the numbers that are a ratio of two integers.
• Irrational($\mathbb{I}$): All the numbers that aren’t a rational number.
• Real($\mathbb{R}$): All the numbers that can be represented on the number line.

Examples

$\N = \set{1, 2, 6, 24, 128, ...}$
$\Z = \set{-10, -4, -1, 0, 1, 4, 10, ...}$
$\mathbb{Q} = \set{-10/2, -5, \sqrt{81}, 9, 10.50/2, 5.25, ...}$
$\mathbb{I} = \set{\sqrt{2}, \sqrt{8}, \pi, e, ...}$
$\mathbb{R} = \set{3.5, -24/8, \pi, \sqrt{2}, 54, -33, 2/8, ...}$

Real Number Line

The real number line is a visual representation of real numbers used to show their order and magnitude, extending infinitely in both directions.