Arithmetic/Types of Numbers/Integer Number

An integer number is any of: a positive whole number (a positive integer), a negative whole number (a negative integer), or zero.

Positive Integer

A Positive Integer is a natural number greater than 0, i.e. a whole number. A Positive Integer can be expressed mathematically:

I > 0 = {+1,+2,+3,+4,+5,+6,+7,+8,+9,...}

Positive numbers are often written without a + sign:

I > 0 = {1,2,3,4,5,6,7,8,9,...}

Negative Integer

A Negative Integer is a negative whole number. This is represented by a - sign on the left side of the value.

I < 0 = {-1,-2,-3,-4,-5,-6,-7,-8,-9,...}

Number Zero

The Integers include a new number, 0.

Rules

1. a + 0 = a
2. a - 0 = a
3. a × 0 = 0
4. a / 0 is not defined.
5. a + a = 2a
6. a - a = 0
7. a × a = a²
8. a / a = 1 (except for a = 0, which is not defined, see rule 4)
9. a - (-a) = 2a
10. a × (-a) = - a²
11. a / (-a) = -1 (except for a = 0, which is not defined, see rule 4)