About calculation

Calculation is the process that a spreadsheet uses to compute formulas in its cells and then display the results as values. By default, formulas are automatically calculated when a change occurs in the cells that the formulas refer to. However, you can change how a spreadsheet calculates.

Stored vs. displayed values   Values are sometimes displayed and stored differently. Dates and times, for example, are stored as serial numbers but are usually displayed and printed in one of several date or time formats. The spreadsheet uses the stored serial numbers in calculations, which makes it possible to calculate the number of days between two dates.

The format that stored values are displayed in sometimes depends on how you choose to format them. For example, you can format a cell that contains the number 123456789 to display as 1.23E+08 by using the Scientific format. Or you can format a cell that contains a date with the serial number 36699 to display as "6/22/2000" or as "22-Jun-2000". Changing the display of a value does not change the stored value.

The regional settings in Microsoft Windows Control Panel also determine how number, currency, date, and time formats are displayed. For example, these settings determine whether years are displayed with two digits or four digits. See Windows Help for information about these formats.