# Absolute Value or Modulus of a Real Number – An Idea of Number System

What is Absolute value or Modulus?
Let a be a real number, then the modulus or absolute value of a is denoted by |a| and

# Irrational Number – An Idea of Number System

What is an Irrational Number?
There is no formal definition of irrational number, but the real number which not rational number is called irrational number.

# Rational Number – An Idea of Number System

What is rational number?
A number of the form p/q, where p, q are integers, prime to each other and q ≠ 0 is called