Sum of first n even numbers = ?
Sum of first n odd number + n
Sum of first n natural numbers - Sum of first n odd numbers
Sum of first n odd numbers - n
Sum of first n odd numbers - Sum of first n natural numbers
Explanation:
Sum of first n even numbers = $n^{2}$ + n
Sum of first n odd numbers = $n^{2}$
So, sum of first n even numbers = Sum of first n odd number + n.