Since Windows 7 was launched last October Microsoft has sold 150 million copies of it.That is about 7 copies per second.For comparison Apple sells an iPad every two seconds.

Windows 7 hit general retail availability on Oct. 22, 2009, meaning Wednesday of this week was the 245th day the operating system was available. With 86,400 seconds in a day, that gave Microsoft 21,168,000 seconds in which to sell 150 million licenses. If exactly 150 million licenses were sold through June 23 that means sales progressed at a brisk 7.086 copies per second.

Thats making it the fastest-selling OS in the company’s history.