Question

Which expression gives the sum of the first n natural numbers \[1 + 2 + \cdots + n\]?

Options

• \[n^2\]

• \[n(n+1)\]

• \[\frac{n(n-1)}{2}\]

• \[\frac{n(n+1)}{2}\]

Answer 1

The sum of the first n natural numbers is \[1 + 2 + \cdots + n = \frac{n(n+1)}{2}.\] For example, \[1 + 2 + 3 = \frac{3(4)}{2} = 6.\]