Prove that n2+n is divisible by 2 for any positive integer n.
Let m=n2+n=n(n+1)
Clearly seen, the m is product of two consecutive
integers. i.e. our even and one odd
∴ when dividing from ′2′ it will be divisible because
there is always an even team preset.
No2=n(n+1)2=∑ of integers from 0 to ∞