Excel's Formula - sisman

Chapter 6: Working with Dates and Times 173
The following formula in cell H17 calculates the weekly total by summing the daily totals in column
H:
=SUM(H8:H14)
This worksheet assumes that hours that exceed 40 hours in a week are considered overtime
hours. The worksheet contains a cell named Overtime (cell C23) that contains 40:00. If your standard
workweek consists of something other than 40 hours, you can change the Overtime cell.
The following formula (in cell E18) calculates regular (non-overtime) hours. This formula returns
the smaller of two values: the total hours, or the overtime hours.
=MIN(E17,Overtime)
The final formula, in cell E19, simply subtracts the regular hours from the total hours to yield the
overtime hours:
=E17-E18
The times in H17:H19 may display time values that exceed 24 hours, so these cells use a custom
number format:
[h]:mm
The workbook shown in Figure 6-7, time sheet.xlsm, also appears on the companion
CD-ROM.
Calculating the difference between two times
Because times are represented as serial numbers, you can subtract the earlier time from the later
time to get the difference. For example, if cell A2 contains 5:30:00 and cell B2 contains 14:00:00,
the following formula returns 08:30:00 (a difference of eight hours and 30 minutes):
=B2-A2
If the subtraction results in a negative value, however, it becomes an invalid time; Excel displays
a series of hash marks (#######) because a time without a date has a date serial number of 0. A
negative time results in a negative serial number, which cannot be displayed — although you can
still use the calculated value in other formulas.