The sum of n natural numbers is 325 . Find n.

If the sum of n natural numbers is one sixth of their squares , then n is :

If the sum of first n even natural number is 240. find the value of n.

If the sum of first n even natural number is 240. find the value of n.

If the sum of first n odd natural number is 1225, find the value of n.

The sequence of odd natural numbers is divided into groups 1,3,5,7,9,11,"…." and so on. Show that the sum of the numbers in nth group is n^(3) .

Statement 1 The difference between the sum of the first 100 even natural numbers and the sum of the first 100 odd natural numbers is 100. Statement 2 The difference between the sum of the first n even natural numbers and sum of the first n odd natural numbers is n.

Sum of all first n terms of even natural number is 2, 4,……2n:

A function f from the set of natural numbers to integers defined by : f(n)={:[((n-1)/(2)",""when n is odd"),(-(n)/(2)",""when n is even"):} is :

The variance of the first n natural numbers is :

Find the sum of natural odd numbers from 1 to 100.