A rational number can be written as a fraction with whole numbers an irrational cannot be written as a fraction 1/4 is a fraction with whole numbers (pi is irrational because it never ends and it's fraction form can only be estimated)
Any number that you can completely write down with digits ... and a fraction bar or decimal point if necessary ... is rational. 1/4 is the complete number so it's rational. It's as easy as that.
