Maths wizardry with lines

[matgb]

You thought you knew maths? YouTube - Alex Bellos demonstrates a very cool, and strange way to multiply:

How weird is that? (Via)

Can't afford to buy the book, does anyone know more about the method, because if multiplying were that easy surely they'd be teaching it in schools, especially for the less numerically gifted?

Comments

[dainul.livejournal.com]

I was going to say something similar - imagine 19*91, you'd have to count up 81 crosses at one corner alone.