I cannot imagine the person who buys these:

People who aren't maths geeks aren't going to want them. And people like me would actually be moved to smash them to pieces. I suppose you might buy one for a maths geek you don't really like, just to watch them squirm.
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Funny how I found myself checking the math in the picture before I even read your post.
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I prefer the ThinkGeek ones - I must get myself a caffeine molecule mug.
http://www.thinkgeek.com/homeoffice/mugs/
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*uses amused mathematician icon*
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