### Python 3 program to find the square root of a number :

To find the *square root* of a number in python, we have two different approaches. In this example, we will learn both of these processes one by one. We are using *python 3* for this example.

### Required knowledge for this example :

1. *if-else* in python.

2. Basics of user input.

### Approaches :

We can find out the *square root* of a number using :

1. Simple *mathematics* or without using any inbuilt *function*.

2. Using *math* module.

### Python3 Program to find square root without using the inbuilt function :

#1 number = int(input("Enter a number to find the square root : ")) #2 if number < 0 : print("Please enter a valid number.") else : #3 sq_root = number ** 0.5 #4 print("Square root of {} is {} ".format(number,sq_root))

### Example Output :

Enter a number to find the square root : 16 Square root of 16 is 4.0 Enter a number to find the square root : 12 Square root of 12 is 3.4641016151377544 Enter a number to find the square root : -12 Please enter a valid number.

### Explanation :

*The commented numbers in the above program denote the step number below :*

1. First, take the input number from the user and save it in variable *number*

2. Check if the number is a negative number. We are calculating square root only for *positive numbers*. If it is negative, prompt the user to enter a valid number.

3. Now, to find the square root of the number we are finding the *number raised to the power 0.5*. It will provide us square root of the *number*. Save this value in variable *sq_root*.

4. Finally, print out the result to the user.

### Python program to find the square root of a number using math module :

import math number = int(input("Enter a number to find square root : ")) if number < 0 : print("Please enter a valid number .") else : print("Square root of {} is {} ".format(number,math.sqrt(number)))

### Sample Output :

Enter a number to find the square root : 16 Square root of 16 is 4.0 Enter a number to find the square root : 12 Square root of 12 is 3.4641016151377544 Enter a number to find the square root : -12 Please enter a valid number.

### Explanation :

The output of this process is same as the above one. The only thing we are changing is :

1. Import the *math* module using *import math* at the beginning of the program.

2. Finding out the *square root* of the *number* using *math.sqrt(number)* method.

You can use any of the following methods to find the square root. But always remember to check if it is *a positive number or not*. Else, it will throw an exception.