Modulus of a Complex Number: The absolute value or modulus of a complex number is denoted by and is given by
Here, as usual, the radical stands for the principal (non-negative) square root of .
Note that is always a non-negative real number and that the only complex number whose modulus is zero is the number . Basically the above definition extends the concept of absolute value of a real number to the complex number system. Example: The modulus of the complex number is .