Natural Numbers (N) are Counting numbers  - 1, 2, 3, 4, and so on. The smallest natural number is 1. Whole Numbers (W) are Natural numbers including 0 - 0, 1, 2, 3, 4 , and son on. The smallest whole number is 0.

Integers (I) are whole numbers including negatives of natural numbers.

Rational and Irrational numbers together constitute the system of real numbers.

Rational Numbers (Q): Number p/q is a rational number if p and q are integers and q ≠ 0. Every integer is a rational number but every rational number is not an integer. Every fraction is a rational number but vice-versa is not always true.

Decimal representation of rational numbers: Process of expressing a rational number into decimal form is to carry out the process of long division using decimal. Rational number is either a terminating decimal or a non-terminating repeating decimal.

Irrational numbers: A decimal expression which is neither terminating nor repeating represents an irrational number.

Exponent: The notation for writing the product of a number by itself several times. For example, a × a × a × a = a4. Here, a is base and 4 is exponent.


Prime factorisation: Any natural number other than 1, can be expressed as a product of power of prime numbers.