Sum of cubes of first n natural numbers Calculator



Calculating the Sum of Cubes of the First n Natural Numbers

The sum of the cubes of the first n natural numbers can be calculated using a specific formula. This formula provides a convenient method to determine the sum without manually calculating the cube of each number and adding them together.

The formula used is:

\(\text{Sum} = \left(\dfrac{ n(n+1)}{2}\right)^2\)

Where:

  • n represents the number of natural numbers.

This can be expressed as:

\( 1^3 + 2^3 + 3^3 + ... + n^3 \)

Examples

Let’s explore some examples to understand how this formula is applied in practice.

1. Calculate the sum of cubes of the first 8 natural numbers.

Answer

To begin, we determine the value of n:

Given:

  • n = 8

Next, we apply the standard formula:

Formula:

\( \text{Sum} = \left(\dfrac{ n(n+1)}{2}\right)^2 \)

We substitute the value of n into the formula to calculate the sum:

Substitution:

\( \text{Sum} = \left(\dfrac{8(8+1)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{8(9)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{72}{2}\right)^2 \)

\( \text{Sum} = (36)^2 \)

\( \text{Sum} = 1296 \)

Finally, we conclude with the result:

Result:

∴ The sum of cubes of the first 8 natural numbers is 1296.

2. What is the sum of the cubes of the first 5 natural numbers?

Answer

We start by determining the value of n:

Given:

  • n = 5

Next, we use the established formula to find the sum:

Formula:

\( \text{Sum} = \left(\dfrac{ n(n+1)}{2}\right)^2 \)

We substitute n into the formula and simplify:

Substitution:

\( \text{Sum} = \left(\dfrac{5(5+1)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{5(6)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{30}{2}\right)^2 \)

\( \text{Sum} = (15)^2 \)

\( \text{Sum} = 225 \)

The result is:

Result:

∴ The sum of cubes of the first 5 natural numbers is 225.

3. Calculate the sum of the cubes of the first 10 natural numbers.

Answer

We first identify the value of n:

Given:

  • n = 10

Next, we apply the formula to calculate the sum:

Formula:

\( \text{Sum} = \left(\dfrac{ n(n+1)}{2}\right)^2 \)

We then substitute n into the formula and perform the calculation:

Substitution:

\( \text{Sum} = \left(\dfrac{10(10+1)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{10(11)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{110}{2}\right)^2 \)

\( \text{Sum} = (55)^2 \)

\( \text{Sum} = 3025 \)

The final result is:

Result:

∴ The sum of cubes of the first 10 natural numbers is 3025.

4. Find the sum of cubes of the first 12 natural numbers.

Answer

We begin by determining n:

Given:

  • n = 12

Next, we use the standard formula to perform the calculation:

Formula:

\( \text{Sum} = \left(\dfrac{ n(n+1)}{2}\right)^2 \)

We substitute the value of n into the formula and simplify:

Substitution:

\( \text{Sum} = \left(\dfrac{12(12+1)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{12(13)}{2}\right)^2 \)

\( \text{Sum} = \left(\dfrac{156}{2}\right)^2 \)

\( \text{Sum} = (78)^2 \)

\( \text{Sum} = 6084 \)

The final sum is:

Result:

∴ The sum of cubes of the first 12 natural numbers is 6084.

Formula

To calculate the sum of cubes of first n natural numbers, you can use the following formula.

\( = \) \({\{ \dfrac{ n ( n +1)}{2}\} }^2\)

Calculation

Once you enter the input values in the calculator, the output parameters are calculated.

Frequently Asked Questions (FAQs)

1. What is the sum of cubes of the first n natural numbers?

2. How do you calculate the sum of cubes of the first n natural numbers?

3. Why does the formula \( \left( \frac{n(n+1)}{2} \right)^2 \) work for the sum of cubes?

4. Can I use this formula for negative numbers?

5. How does a calculator for the sum of cubes of first n natural numbers work?

6. What is the sum of cubes for the first 5 natural numbers?

7. Is the sum of cubes of n natural numbers always a perfect square?

8. Why is finding the sum of cubes of the first n natural numbers useful?