The sum of first n odd natural numbers is n(n + 1).
If the sum of first n even natural numbers is equal to k times the sum of the first n odd natural numbers, then k =
Prove that: 1 + 2 + 3 + ......... + n = n(n+1)2 i.e., the sum of the first n natural numbers is n(n+1)2.
The sum S of first n even natural numbers in given by the relation S = n(n + 1). Find n, if the sum is 420.