You find a number you can divide both the numerator and denominator by. You may want to start from 2 and just keep going until you find the smallest number possible for your numerator and...
we simplify because in life, you'll come across number like 4534563645/4215245 that you just CANT figure out... if you don't simplify, you'll have to guess what it is. then if its 1/3 and you put 3/4...