Brad Templeton introduced in 2001 a nice index: the Bill Gates Wealth Index. The idea is to imagine Gates seeing or dropping a piece of paper money on the ground: How large a denomination would the bill have to make it worth his time to stop and pick up ?Templeton calculated that during 1986, a $5 bill would have been 'too small for Bill' to bother with. By 1998, a $10,000 bill wasn't worth the trouble.