Bill Gates must have been thinking that why Windows latest version wasn't beennamed  windows 8 or 10 -  as microsoft says officially that Windows '7' sells '7' copies per second (hope you got the pun I am trying to make ) .

In a official windows blog post it was announced that Windows 7 has sold 150 million licenses to-date which works out to be seven per second.Windows 7 is by far the “fastest selling operating system in history,” according to Microsoft. Microsoft estimates that 75 percent of enterprises are currently evaluating Windows 7. Any guesses on how fast we get to 300 million copies sold?