The S.D. of the first n natural numbers is

The S.D. of first n odd natural numbers is:

The S.D for the set of the first 'n' natural numbers is

The sum of the first 'n' natural numbers is given by the formula S=(n(n+1))/2 . Find 'n' if the sum is 465.

Mean of first n natural numbers is

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.

Find the sum of : the first n natural numbers