Definition of Numbers and Their Types
Numbers
A Number is a mathematical object used to count, measure or label objects. We have 10 digits to denote, they are 0,1,2,3,4,5,6,7,8,9. A number is denoted by a group of digits called numeral.
Types of Numbers
1. Rational Numbers: A rational number is any number that can be expressed in the form p /q where denominator q is not equal to zero.
Ex: 2/7, 5/11,etc.
2. Integers: An integer is a number that can be written without a fractional component or a decimal point. The set of integers is denoted by I or z.
Integers can be divided into following types :
a. Natural and Whole Numbers:
The numbers 1,2,3,.. So on are the natural numbers. The set of natural numbers is denoted by N.
The numbers 0,1,2,3,4,.. are the whole number. The set of whole number is denoted by W.
b. Positive and Negative Numbers :
Integers greater than zero are positive integers.
Ex: 4,46,etc.
Integers less than zero are negative numbers.
Ex: -4,-36,etc.
c. Non -Negative Numbers :
The integers which are not negative are called non -negative integers.
Ex: 4,0,etc.
d. Even and Odd Numbers :
The integers that are perfectly divisible by 2 are called even numbers.
Ex: 2,4,etc.
The integers that leave a remainder of 1 when divided by 2 are odd numbers.
Ex: 3,63,etc.
e. Prime and Composite Numbers :
Natural numbers that do not have any other factor than 1 and itself are called prime numbers.
Ex: 2,3,73,etc.
The other numbers that have more factors also other than 1 and itself are called composite numbers.
Ex: 4,24,etc.
f. Real Number :
Set of numbers that include both rational and irrational numbers is called real numbers.
g. Imaginary Number :
It is denoted by i.
h. Complex Number :
A complex number consists of two parts: a real number and imaginary number and it is expressed in the form of a+bi.
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