If I have a stack of pennies. And I have to tell that without counting whether there are even number of pennies or odd.
Even numbers are the numbers which are divisible by 2 and odd numbers are the numbers which are not divisible by 2.
Then I will put the given pennies in 2 rows and then I will match them to form a pair of 2 pennies.
After matching, if there is 1 penny left over, then there is an odd number of pennies and if all the pennies have a match,then there is an even number of pennies.
