Power of a Number using Recursion in Python

October 11, 2022

Power of number in Python

Power  of  a  Number

On this page we will see how to find Power of a Number in Python. We will see three methods to do so. User have to give base and power as input. Power of a number is basically multiplying the base number by itself , power number of time.

Example :

  • Input  :  base = 2, power = 3
  • Output  :  8
  • Explanation  :   23 means 2 is base and 3 is power which is 3 times 2 (  2 x 2 x 2 ) which is equals to 8

Method 1 : Using Recursion

Algorithm

  • We will first assign value of a as base and b as power of number.
  • We will pass a and b to function power.
  • We will use recursion to find the answer.
  • We will recursively call the function power and each time we will return a*power(a,b-1) till the time b is not equal to zero. Each recursion call will return a multiply by a till b is not zero. In each call we will decrement the value of b by 1.
  • If b is equal to zero then we will return from the function.
Python Program for Power of a Number

Python Code

Run 
def power(a, b):
    if b != 0:
        return a * power(a, b - 1)
    else:
        return 1


a = 2
b = 3
print(a, "to the power", b, "is", power(a, b))
Output:

2 to the power 3 is 8
 
 

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Method 2 : Using For Loop

Algorithm

  • We will first assign value of a as base and b as power of number.
  • We will pass a and b to function power.
  • We will declare a new variable ans to store final answer.
  • We will use for loop to find power using variable i.
  • For loop will run from o till b-1. And for each iteration we will multiply a with a.
  • After completing iterating from for loop we will then return ans.

Python Code

Run 
def power(a, b):
    ans = a
    for i in range(b - 1):
        ans = a * ans
    return ans


a = 2
b = 3
print(a, "to the power", b, "is", power(a, b))
Output:

2 to the power 3 is 8

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Method 3 : Using While Loop

Algorithm

  • We will first assign value of a as base and b as power of number.
  • We will pass a and b to function power.
  • We will declare a variable name ans and assign 1 to it.
  • We will use while loop to iterate.
  • We will run while loop till the time b is not zero.
  • For each iteration ans=ans*a, and we will decrement b by 1.
  • At the end we will return ans variable.

Python Code

def power(a, b):
    ans = 1
    while b != 0:
        ans = ans * a
        b = b - 1
    return ans


a = 2
b = 3
print(a, "to the power", b, "is", power(a, b))
Output:

2 to the power 3 is 8

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