(iii) For the natural number 1 there is no previous natural number

(iii) For the natural number 1there is no previous natural number

The natural number 1 has no predecessor.

Between any two natural numbers, there is one natural number.

For some natural number 'n', the sum of the 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.