Page 82 - Excel 2007 Bible

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Entering date values
Excel handles dates by using a serial number system. The earliest date that Excel understands is January 1,
1900. This date has a serial number of 1. January 2, 1900, has a serial number of 2, and so on. This system
makes it easy to deal with dates in formulas. For example, you can enter a formula to calculate the number
of days between two dates.
Most of the time, you don’t have to be concerned with Excel’s serial number date system. You can simply
enter a date in a familiar date format, and Excel takes care of the details behind the scenes.
For example, if you need to enter June 1, 2007, you can simply enter the date by typing June 1, 2007 (or
use any of several different date formats). Excel interprets your entry and stores the value 39234, which is
the date serial number for that date.
The date examples in this book use the U.S. English system. Depending on your regional
NOTE
NOTE
settings, entering a date in a format (such as June 1, 2007) may be interpreted as text rather
than a date. In such a case, you need to enter the date in a format that corresponds to your regional date
settings — for example, 1 June, 2007.
For more information about working with dates and times, refer to Chapter 13.
CROSS-REF
CROSS-REF
Entering time values Entering and Editing Worksheet Data 3
When you work with times, you simply extend Excel’s date serial number system to include decimals. In
other words, Excel works with times by using fractional days. For example, the date serial number for June
1, 2007, is 39234. Noon on June 1, 2007 (halfway through the day), is represented internally as 39234.5
because the time fraction is simply added to the date serial number to get the full date/time serial number.
Again, you normally don’t have to be concerned with these serial numbers (or fractional serial numbers, for
times). Just enter the time into a cell in a recognized format.
CROSS-REF Refer to Chapter 13 for more information about working with time values.
CROSS-REF
Modifying Cell Contents
After you enter a value or text into a cell, you can modify it in several ways:
n Erase the cell’s contents
n Replace the cell’s contents with something else
n Edit the cell’s contents
Erasing the contents of a cell
To erase the contents of a cell, just click the cell and press Delete. To erase more than one cell, select all the
cells that you want to erase and then press Delete. Pressing Delete removes the cell’s contents but doesn’t
remove any formatting (such as bold, italic, or a different number format) that you may have applied to
the cell.

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