Excel 2010 Bible

Chapter 12: Working with Dates and Times

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In Excel, the smallest unit of time is one one-thousandth of a second. The time serial number

shown here represents 23:59:59.999 (one one-thousandth of a second before midnight):

0.99999999

Table 12.2 shows various times of day along with each associated time serial numbers.

TABLE 12.2

Times of Day and Their Corresponding Serial Numbers

Time of Day Time Serial Number

12:00:00 AM (midnight) 0.00000000

1:30:00 AM 0.06250000

7:30:00 AM 0.31250000

10:30:00 AM 0.43750000

12:00:00 PM (noon) 0.50000000

1:30:00 PM 0.56250000

4:30:00 PM 0.68750000

6:00:00 PM 0.75000000

9:00:00 PM 0.87500000

10:30:00 PM 0.93750000

Entering times .........................................................................................................

As with entering dates, you normally don’t have to worry about the actual time serial numbers. Just

enter the time into a cell using a recognized format. Table 12.3 shows some examples of time for-

mats that Excel recognizes.

TABLE 12.3

Time Entry Formats Recognized by Excel

Entry Excel Interpretation

11:30:00 am 11:30 AM

11:30:00 AM 11:30 AM

11:30 pm 11:30 PM

11:30 11:30 AM

13:30 1:30 PM