When you change the value in any of the cells to which a formula refers, Excel updates the displayed values of the formula as well. This updating process is called recalculation, and it affects only those cells containing references to cells that have changed. By default, Excel recalculates whenever you make changes to a cell. If a large number of cells must be recalculated, the word Calculating appears in the status bar, along with a percentage of progress meter if it’s going to take a particularly long time. You can interrupt the recalculation process simply by doing something, such as using commands or making cell entries; Excel pauses and then resumes recalculation when you are finished.
When you open an Excel 2007 ...