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Uploaded on Aug 7, 2011
This video explains the mechanics of multiplying extended facts. For example, 7x2 =14, and by extension 7 x 20 = 140. The meaning of *why* this is possible is not fully explained, although it is somewhat covered by showing a pictorial solution to the problem. A related video of what it means to multiply by a power of ten should be made and linked to this video. That plus understanding of the commutative property of multiplication is what makes this "trick" work.