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Python program for sum of cube of first N natural numbers

Here, we will write a Python program to find the sum of cube of first N natural numbers.
Submitted by Shivang Yadav, on April 03, 2021

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Sum of cube of first N Natural Numbers

1³ + 2³ + 3³ + 4³ + … N³

We will get the value of N as input from the user and then print the sum of cubes of the first N natural numbers.

Example:

Input:
N = 5

Output:
225

Method 1: Using Loop

A simple solution is to loop from 1 to N, and add their cubes to sumVal.

Program to find the sum of the cubes of first N natural number

# Python program for sum of the 
# cubes of first N natural numbers

# Getting input from users
N = int(input("Enter value of N: "))

# calculating sum of cube 
sumVal = 0
for i in range(1, N+1):
    sumVal += (i*i*i)

print("Sum of cubes = ", sumVal)

Output:

RUN 1:
Enter value of N: 10
Sum of cubes =  3025

RUN 2:
Enter value of N: 12
Sum of cubes =  6084

Explanation:

In the above code, we have taken input from the user for the value of N. And then we have initialized the sumVal to 0 and looping from 1 to N, we will add the value (i³) to the sumVal. At last, printed the sumVal.

Method 2: Using mathematical formula

A direct approach to find the sum of the cubes is using the mathematical formula.

The formula is,

sum = { (N * (N+1)) / 2 }²

Program for the sum of the cubes of first N natural numbers

# Python program for sum of the 
# cubes of first N natural numbers

# Getting input from user
N = int(input("Enter value of N: "))

# calculating sum of cubes 
sumVal =  (int)( pow(( (N * (N+1))/2 ) , 2) )
print("Sum of cubes =",sumVal)

Output:

RUN 1:
Enter value of N: 10
Sum of cubes =  3025

RUN 2:
Enter value of N: 12
Sum of cubes =  6084

Explanation:

In the above code, we have taken input from the user for the value of N. And then we have used the formula to get the sum and store it to sumVal and print it.

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