Lattice Multiplication

I had never heard of "lattice multiplication" until I saw this video, and it sort of blew my mind. Check it out!

Note: This video is from the fantastic Khan Academy collection of educational videos.

Counting Systems

The following video, although titled "History of Mathematics," is really more of a look at various counting and numbering systems used by different cultures throughout history. It also mentions a few ways that fractions were used and how computations like multiplication have been tackled.

Three is a Magic Number

Ah, nostalgia... Here's a bit of the 70s/80s for your Friday with that classic Schoolhouse Rock! segment "Three is a Magic Number." Enjoy!