Brian Monetti, I <3 math!
A rational number is one which can be expressed as the quotient (which is the result of diving) of two intergers,or whole numbers. Therefore, 4 is a rational number since 8/2=4. Also, .5 is a rational number, since 1/2=.5 and so is .125 which is equal to 1/8. An number which is not rational would be something like pi or the square route of 2. Both of these numbers can not be represented a a fraction of two whole numbers. Instead, the numbers continue on for infinity without ending.