# Python Program for cube sum of first n natural numbers

In this article, we will learn to find the sum of the cube of the first n number using the python program.

the sum of the cube of n numbers:

13 + 23 + 33 + 43 + ....... + (n-1)3 + n3

We find the sum of the cube of positive numbers from 1 to nth using two method

• using for loop
• using mathematically

### Method 1: Using for loop

Time Complexity for this program is: O(N)

#### Program

 ``` 1 2 3 4 5 6 7 8 9 10``` ```# Sum of the cube of positive numbers from 1 to nth using forloop n = int(input("Enter nth number: ")) sum = 0 for i in range(1,n+1): sum = sum + (i*i*i) print("Sum of the cube of the number from 1 to",n,"is: ",sum) # Sum of the cube of positive numbers from of nth using forloop - docodehere.com ```

#### Output

```Enter nth number: 10
Sum of the cube of the number from 1 to 10 is:  3025
```

### Method 2: Using Mathematical formula

Time Complexity for this program is: O(1)

#### Program

 ```1 2 3 4 5 6``` ```# Sum of the cube of positive numbers from 1 to nth without forloop n = int(input("Enter nth number: ")) print(( n * (n + 1) / 2 ) ** 2) # Sum of the cube of positive numbers from of nth without forloop - docodehere.com ```

#### Output

```Enter nth number: 3
36
```
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