Variance of first 20 natural numbers is

There are natural numbers. Answer the following questions considering first natural numbers. Variance of first n natural numbers is -

The variance for first 20 natural numbers is

If the variance of first n natural numbers is 2 and the variance of first m odd natural numbers is 40, then m +n =

If the variance of first n natural numbers is 2 and the variance of first m odd natural numbers is 40, then m +n =

Variance of first n natural number is …………