When you see a number saying something like Bill Gates is worth 40 billion, where does that number even come from? Even more confusing is when it's included that the majority of that is in stock. Alright so let's do some math here. Microsoft's stock price on Dec 29, 2006 is $29.86 and share volume is 41.76 million. Multiply those together and Microsoft is worth 1247 million, or $1,247,000,000 (1.25 billion). Wouldn't Bill need to own 100% of Microsoft's stock about 30 times over before being worth 40 billion?