Page 266 - Excel 2007 Bible

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Working with Dates
and Times
eginners often find that working with dates and times in Excel can be
frustrating. To work with dates and times, you need a good understanding IN THIS CHAPTER
Bof how Excel handles time-based information. This chapter provides the An overview of using dates and
information you need to create powerful formulas that manipulate dates and times in Excel
times.
NOTE The dates in this chapter correspond to the United States English Excel’s date-related functions
NOTE
date format: month/day/year. For example, the date 3/1/1952
refers to March 1, 1952, not January 3, 1952. I realize that this setup may seem Excel’s time-related functions
illogical, but that’s the way Americans have been trained. I trust that the non-
American readers of this book can make the adjustment.
How Excel Handles Dates and Times

This section presents a quick overview of how Excel deals with dates and times.
It includes coverage of the Excel program’s date and time serial number system,
and it offers tips for entering and formatting dates and times.

Understanding date serial numbers
To Excel, a date is simply a number. More precisely, a date is a serial number that
represents the number of days since the fictitious date of January 0, 1900. A
serial number of 1 corresponds to January 1, 1900; a serial number of 2 corre-
sponds to January 2, 1900, and so on. This system makes it possible to deal with
dates in formulas. For example, you can create a formula to calculate the number
of days between two dates (just subtract one from the other).
Excel support dates from January 1, 1900, through December 31, 9999 (serial
number = 2,958,465).

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