# Recursive function to find out GCD

GCD is known as the greatest common divisor. It is the largest number that is able to divide both numbers. The process of finding the greatest number is as follows

• Divide first number by the second number. if the second number is able to divide it completely then the first number is GCD of both
• If the second number is not able to divide completely then the divider becomes number for the next step and the remainder becomes the divider.
• Continue this process unless divider divides the number completely

## Python recursion Function to find out GCD

```def gcd(a, b):
if(b == 0):
return a
else:
return gcd(b, a % b)

if __name__ == "__main__":
a = int(input('Enter first number '))
b = int(input('Enter second number '))
result = gcd(a, b)
print('GCD of {} and {} is {}'.format(a, b, result))

```

The same program can be written using iterative methods also.

## GCD using Looping method

```#   program to find out GCD of two number using iterative method
#   made by     : rakeseh kumar

a = int(input('Enter any number'))
b = int(input('Enter another number'))

""" if(a > b):
number = a
divider = b
else:
number = b
divider = a """

rem = a % b

while(rem != 0):
a = b
b = rem
rem = a % b

`Here is the output of the above program`
```rakesh@folio MINGW64 /e/python (master)