Over the past few​ years, Microsoft founder Bill​ Gates' net worth has fluctuated between​ $20 billion and​ $130 billion. In early​ 2006, it was about​ $26 billionafter he reduced his stake in Microsoft from 21 percent to around 14 percent by moving billions into his charitable foundation. ​ Let's see what Bill Gates can do with his money in the following problems.