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In these lessons, we will learn about digits, integers, even and odd integers, operations on even and odd numbers, prime numbers and composite numbers.

We will also learn the following properties of Integers: Commutative Property for Addition, Associative Property for Addition, Distributive Property, Identity Property for Addition, Identity Property for Multiplication, Inverse Property for Addition and Zero Property for Multiplication.

Related Topics: More Lessons on Integers

Digits are the first concept of integers. There are ten digits namely: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

In our number system, the position of the digits are important. For example, consider the number 3,027. This can be represented in a place value table as follows:

Thousands

Hundreds

Tens

Units/Ones

3

0

2

7

Integers are whole numbers, for example, –4, –3, –2, –1, 0, 1, 2, 3, 4, ...

Positive integers are all the whole numbers greater than zero, ie: 1, 2, 3, 4, 5, ... We say that its sign is positive. Negative integers are all the whole numbers less than zero, ie: –1, –2, –3, –4, –5, ... We say that its sign is negative.

Integers extend infinitely in both positive and negative directions. This can be represented on the number line.

**Zero** is an integer that is neither positive nor
negative.

Consecutive integers are integers that follow in sequence, each number being 1 more than the previous number, for example 22, 23, 24, 25, ...

Consecutive integers can be more generally represented by *n*, *n* +1, *n* + 2, *n* + 3, ..., where n is any integer.

Even integers are integers that can be divided evenly by 2, for example,
–4, –2, 0, 2, 4, ... An even integer always ends in **0, 2, 4, 6,** or **8**.

**Zero** is considered an even integer. Odd integers are integers that cannot be
divided evenly by 2, for example, –5, –3, –1, 1, 3, 5, ... An odd integer always
ends in **1, 3, 5, 7, or 9**. To tell whether an integer is even or odd, look at the digit in the
ones place. That single digit will tell you whether the entire integer is odd or even, for example the
integer 3,255 is an odd integer because it ends in 5, an odd integer. Likewise, 702 is an even integer
because it ends in 2.

Addition |
examples: |

even + even = even | 2 + 4 = 6 |

odd + odd = even | 1 + 3 = 4 |

odd + even = odd | 1 + 2 = 3 |

Multiplication |
examples: |

even × even = even | 2 × 4 = 8 |

odd × odd = odd | 1 × 3 = 3 |

odd × even = even | 3 × 2 = 6 |

A prime number is a positive integer that has exactly two factors, 1 and itself, for example 29 has exactly two factors which are 1 and 29. So 29 is a prime number.

On the other hand, 28 has six factors which are 1, 2, 4, 7, 14, and 28. So
28 is not a prime number. It is called a composite number. Some examples of prime numbers
are: 2, 3, 5, 7, 11, 13, 17, 19, ... Since the number **1** has only one factor
(namely 1 itself), it is **not** a prime number.

The number **2** is the only **prime that is even**. Other even
numbers will have 2 have as a factor and so will not be a prime.

A number that is not prime is called a composite number.

Learn a systematic technique for drawing conclusions about expressions involving even and odd numbers.

Commutative Property for Addition, Associative Property for Addition, Distributive Property, Identity Property for Addition, Identity Property for Multiplication, Inverse Property for Addition and Zero Property for Multiplication.

3 Properties of integers are explained. Additive Identity, Additive Inverse, Opposite of a negative is positive. Examples are provided.