Excel's Formula - sisman

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Part II: Using Functions in Your Formulas
Excel 2010 includes an updated version of the NETWORKDAYS function, named
NETWORKDAYS.INTL. This new version is useful if you consider weekend days to be
days other than Saturday and Sunday.
This workbook, work days.xlsx, is available on the companion CD-ROM.
Offsetting a date using only work days
The WORKDAY function is the opposite of the NETWORKDAYS function. For example, if you
start a project on January 8 and the project requires ten working days to complete, the
WORKDAY function can calculate the date that you will finish the project.
The following formula uses the WORKDAY function to determine the date ten working days from
January 8, 2010. A working day is a weekday (Monday through Friday).
=WORKDAY(“1/8/2010”,10)
The formula returns a date serial number, which must be formatted as a date. The result is
January 22, 2010 (four weekend dates fall between January 8 and January 22).
The preceding formula may return a different result, depending on your regional date
setting. (The hard-coded date may be interpreted as August 1, 2010.) A better formula is
=WORKDAY(DATE(2010,1,8),10)
The second argument for the WORKDAY function can be negative. And, as with the
NETWORKDAYS function, the WORKDAY function accepts an optional third argument (a reference
to a range that contains a list of holiday dates).
Calculating the number of years between two dates
The following formula calculates the number of years between two dates. This formula assumes
that cells A1 and B1 both contain dates:
=YEAR(A1)-YEAR(B1)
This formula uses the YEAR function to extract the year from each date and then subtracts one
year from the other. If cell B1 contains a more recent date than the date in cell A1, then the result
is negative.