JEE Main 2016 (27)

Algebra Level 3

For some natural number $n$ , the sum of first $n$ natural numbers is 240 less than the sum of the first $(n+5)$ natural numbers. Then $n$ itself is the sum of how many natural numbers starting with 1?

Try my set JEE Main 2016.

10 6 None of these choices 9 7 8