Add or subtract fractions in a graphical way. It’s a simple application of the first graphical multiplication trick. In fact, you will combine three multiplications to get a common denominator. The final drawing will have a "M" shape. The upper part shows the numerator, the lower shows the denominator. This trick is NOT meant to be efficient or even useful in everyday life, it's just a graphical, esthetic way to put a calculus.  I have also added some info about multiplying by zero since it has been asked before. If you don't understand the video and haven't seen the first multiplication trick, you might want to check it at: www.metacafe.com/watch/296904/easy_mental_multiplication_trick