Question

Find the sum \[2 + 4 + 6 + \cdots + 20\] using the sum of the first n even natural numbers.

Options

• \[110\]

• \[210\]

• \[55\]

• \[100\]

Answer 1

Here \[2n = 20\], so \[n = 10.\] Using \[2 + 4 + \cdots + 2n = n(n+1),\] we get \[10(11) = 110.\]