The SendKeys statement sends keystrokes to the application - basically it is simulating a user pressing keys on the keyboard. In this case the string "%^{F9}" simulates the user pressing ALT-CTRL-F9. If you are interested, you can find more information about the SendKeys syntax here...

http://msdn.microsoft.com/en-us/libr...ffice.10).aspx

The ALT-CTRL-F9 shortcut causes the recalculation of all cells on all worksheets in all open workbooks. The CalculateFull statement tells Excel to do the same thing, so we can use it instead of the SendKeys statement without changing the behaviour of the macro.