# MandysNotes

## Sets of Numbers Examples Sets: Natural Numbers, Whole numbers, Integers

20 March 2010

Counting Numbers:

### {1, 2, 3, 4, 5, 6, ...}

BY THE WAY, "..." notates continuation going up infinitely.

The set of Natural Numbers $$\mathbb{N}\ \$$ = {0, 1, 2 3, 4, 5, 6...}.

The set of Integers, $$\mathbb{Z}\ \$$   = {..., -3, -2, -1, 0, 1, 2, 3}.

The set of Rational numbers, $$\mathbb{Q}\ \$$  is the set of ratios of integers.

That is, every $$q \in \mathbb{Q}\$$

is of the form:

$$q = \frac{n}{m} \$$

With $$n, m \in \mathbb{Z}\$$ .

The set of Real Numbers $$\mathbb{R}\ \$$  is the set of limits of sequences of rational numbers.