Fill in the blanks:
The sum of first n even natural numbers is equal to …………..

The sum of first 30 natural numbers is:

Find the sum of first n natural numbers.

Find the sum of first 100 natural numbers.

Find the arithmetic mean of first ten even natural numbers.

The arithmetic mean of first n odd natural numbers is :

Find the sum of first hundred even natural numbers divisible by 5.

If the sum of first n even natural numbers is equal to k times the sum of first n odd natural numbers, then k is equal to:

Fill in the blanks: 1 kg f = ___ N.