Introduction To Numbers

A value that is used for counting, measuring or calculating something is a number. A digit is a symbol used to denote a single number.

KINDS OF NUMBERS

There are two main types of numbers:

• Real numbers
• Imaginary numbers

All kinds of numbers that we study normally in math are all Real Numbers .
Real numbers have the following types:

• Rational Numbers
• Irrational Numbers
• Natural Numbers
• Whole Numbers
• Even Numbers
• Odd Numbers
• Integers
• Prime Numbers
• Composite Numbers

Rational numbers:
Numbers that can be written in the form of a fraction are known as Rational numbers.
The word Rational is derived/taken out from the word ratio that means fraction.
For example, 1/2, 2/3, 6/1 etc. are rational numbers.
We use rational numbers mainly in measurements.
Irrational Numbers:
Opposite to rational numbers. Numbers that cannot be written in the form of a fraction are called Irrational Numbers.
For example, 2.444... is an irrational number.
Natural Numbers:
Numbers that are used for counting are known as Natural Numbers.
For example, 1,2,3,4,5, . are all natural numbers.
Whole Numbers:
All natural numbers including zero are called whole numbers.
0,1,2,3,4,5, are whole numbers.
Even Numbers:
Numbers that come in the table of 2 or are divisible by 2 are even numbers. For example, 0,2,4,6,8, 10, are even numbers.
Odd Numbers:
Numbers that are NOT divisible by 2 are odd numbers. For example, 1,3,5,7,9,11, are odd numbers.
Integers:
All positive and negative numbers including zero are called integers.
Prime Numbers:
Numbers that have ONLY two different factors are prime numbers. These factors are 1 and the number itself.
For example, 2 is a prime number.
How?
2 has only two factors: 1 and 2.
Composite numbers:
Numbers that have more than two different factors are called composite numbers.
For example, 9 is a composite number.
Why?
9 = 1 , 3 , 9.
It has more than two different factors.