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

A square root of a number *X* is a number *Y* if the square of *Y* is equal to *X* or the value of *Y * Y* is equal to *X*. In this tutorial, we will learn how to find out the square root of a number in *Python*.

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

### Required knowledge for this example :

*if-else*in python.- Basics of user input.

If you are learning python, and familiar with its basic concepts, you can easily grab this tutorial.

### Approaches :

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

- Simple
*mathematics*or without using any inbuilt*function*. - Using the
*math*module.

**The source code is available here.**

### 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))
```

### Explanation :

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

- First, take the input number from the user and save it in a
*variable*number. - 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. - Now, to find the square root of the number, we are finding the number raised to the power
*0.5*. It will give us the square root of the number. Save this value in variable*sq_root*. e.g. if we are finding out the square root of*4*, we will find*4*to the power*0.5*, which is*2*. Similarly, we can find out the square root of any number. - 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)))
```

### Explanation :

The output of this process is the same. We are changing the following two points here :

- Import the
*math module*using*import math*at the beginning of the program. If we use this import, we can use all methods defined inside this module. The method used to find the*square root*of a number is defined inside this*math*module. - Find the
*square root*of the number using*math.sqrt(number)*method. This method takes one number as the parameter. It calculates the square root of that number and returns the result. We are using the*format()*method to print out the result to the user. This method takes two arguments: the first one is the*number*and the second one is the return value of the*sqrt()*function, i.e. the*square root*of the number.

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.