Meenakshi finds that the sum of the first n odd numbers is 1,369. What is the sum of the first n even numbers?

Explanation

1. 01

   Sum of the first n odd numbers = $n^2 = 1{,}369$, so $n = 37$.

2. 02

   Sum of the first n even numbers = $n(n + 1) = 37 \times 38 = 1{,}406$.