Go here to learn details. This method is a graphical representation of the foiling of numbers. For example, 42*21= (40+2)*(20+1)= 40*20+40*1+2*20+2*1= 862 - number of intersections of lines corresponding to the number of digits in each position of the two numbers is equal to the corresponding digits in the product. 

Here is another example:

Boring? How about this cool video? Does anyone in it look familiar?  

Want to be more creative? Create your own problems and add your music, image, or video.