Earlier this week I received a request for help from Nancy.
She was having a problem with a date formula. She wanted to subtract 8 days
from the current date.
Well that’s easy enough. =Today()8 Since the day I wrote this post is Sept 25^{th},
the result is September 17^{th} (8 days prior).
A

B

C

D

Result

Formula

Current Date

9/25/2012

9/17/2012

=TODAY()8

However she wanted to only count business days (Nancy did
not want to include Saturday or Sunday).
So that changes the formula.
I needed to look only at Workdays. Fortunately Excel has
just the function for this.
=WORKDAY(TODAY(),8)
Since the day I wrote this post is Sept 25^{th}, the
result is September 13^{th} (8 workdays prior).

A

B

C

D

1

Result

Formula

Current Date

9/25/2012

2

9/17/2012

=TODAY()8



3





4

9/13/2012

=WORKDAY(TODAY(),8)



So what does the WORKDAY function do?
Well according to the Excel Help… Workday returns a number
that represents a date that is the indicated number of working days before or
after a date (the starting date). Working days exclude weekends and any dates
identified as holidays. Use WORKDAY to exclude weekends or holidays when you
calculate invoice due dates, expected delivery times, or the number of days of
work performed.”
Now what is really handy here is the ability to identify
holidays.
Syntax
WORKDAY(start_date,days,holidays)
Start_date is a date that represents the start date.
Days is the
number of nonweekend and nonholiday days before or after start_date. A positive
value for days yields a future date; a negative value yields a past date.
Holidays is an optional list of one or more dates
to exclude from the working calendar, such as state and federal holidays and
floating holidays. The list can be either a range of cells that contain the
dates or an array constant (array: Used to build single formulas that produce
multiple results or that operate on a group of arguments that are arranged in
rows and columns. An array range shares a common formula; an array constant is a group of constants used as an
argument.) of the serial numbers that represent the dates.
Remarks from Microsoft…
Important Dates
should be entered by using the DATE function, or as results of other formulas
or functions. For example, use DATE(2008,5,23) for the 23rd day of May, 2008.
Problems can occur if dates are entered as text .
Microsoft Excel stores dates as sequential serial numbers so
they can be used in calculations. By default, January 1, 1900 is serial number
1, and January 1, 2008 is serial number 39448 because it is 39,448 days after
January 1, 1900. Microsoft Excel for the Macintosh uses a different date system
as its default.
If any argument is not a valid date, WORKDAY returns the
#VALUE! error value.
If start_date plus days yields an invalid date, WORKDAY
returns the #NUM! error value.
If days is not an integer, it is truncated.