Question

What is the sum of the cubes of the first 7 natural numbers?

• A. 784
• B. 774
• C. 441
• D. 788

Answer 1

The correct option is A

784

Sum of cubes of first n natural numbers is $\frac{\left(n\right(n+1){)}^2}{4}$

Putting n = 7,
$\frac{\left(7\right(7+1){)}^2}{4}$
$\frac{(7\times 8{)}^2}{4}$

= 784.