5,683,219,082 as of 2012
...please elaborate.
Over one billion people use Microsoft Office. Microsoft does offer many other products, but Microsof Office is by far the most used. Assuming that most of the people who own Microsoft Office own other Microsoft products as well; a little more than one seventh of the world's population uses Microsoft software.
Microsoft Outlook's userbase in the United States is around 241 million. This is only people who use it as their primary email client. The number is higher for users of just Microsoft Office.
Around 6 million
more than 10 peoples
There are lots of programs that can be used to create databases. People use programs like Microsoft Access. They use Oracle. They use dBase. They use MySQL. They use many others. People can also write their own programs to do it.
Many people use Microsoft Excel to perform calculations. They also use it to establish databases for their business. Excel makes people efficient.
Plenty of people use Windows
They really liked their new suite of furniture. Many people use the Microsoft Office suite.
Microsoft Excel can be used by anyone. It is a very versatile application with many uses, so anybody can make use of it, from business people to a child.
There is no single answer for that. Some people use it every day. Some people never use it. Some use it occasionally. Some use similar office suites, but not Microsoft Office.
People who have a business.