1.print the sum and product from 1 to 20.
2.print the numbers which is not divisible by 3 , from 1 to 20.
3.print even numbers between 1 and 20.
4.print average of numbers from 1 to 20 (should work for any numbers)
5.for numbers from 1 to 20
check if the number is divisible by 2,3 or 5
or all the three
or none of the three
(should work for any range of numbers)