Working with Excel's More Date Functions

In addition to the straightforward Date functions such as TODAY, NOW, DATE, and DATEVALUE, Excels includes a bunch of more sophisticated and powerful Date functions that you can use to calculate elapsed dates, future dates, days of the week, weeks of the year, and the like. These more sophisticated Date function are all available on the Date and Time button's drop-down menu and take an array of different required and optional arguments. Among the most important of these Date functions on this drop-down menu are:

• EDATE(start_date,months)
  calculates the elapsed date so many months ahead (positive months argument) or behind (negative months argument) the start_date argument you specify.
• EOMONTH(start_date,months)
  calculates the last day of the month so many months ahead (positive months argument) or behind (negative months argument) the start_date argument you specify.
• NETWORKDAYS(start_date.end_date,[holidays])
  calculates the number of work days between the start_date and end_date arguments the optional holidays argument can specify a range of holiday dates to be excluded from the workday total.
• WEEKDAY(serial_number,[return_type])
  calculates a number indicating the day of the week specified by the serial_number argument the optional return_type argument can be the number 1, 2, or 3 where 1 (or no return_type argument specified) starts the week on Sunday (1) and ends it on Saturday (7), 2 starts the week on Monday (1) and ends it on Sunday (7), and 3 starts the week on Monday (0) and ends it on Sunday (6).
• WEEKNUM(serial_number,[return_type])
  calculates a number indicating where the week in the date specified by the serial_number argument falls within the year the optional return_type argument can be the number 1 or 2, where 1 (or no return_type argument specified) starts the week on Sunday (1) and ends it on Saturday (7) and 2 starts the week on Monday (1) and ends it on Sunday (7).
• WORKDAY(start_date,days,[holidays])
  calculates the work date that is so many days ahead (positive days argument) or behind (negative days argument) the start_date argument you specify the optional holidays argument can specify a range of holiday dates to be excluded from the calculation.
• YEARFRAC(start_date,end_date,[basis])
  calculates the fraction of the year between the start_date and end_date arguments you specify the optional basis argument can be a number between 0 and 4 that signifies the following:
  
  • 0 (or no basis argument) bases the year fraction on the U.S. (NASD) method of 30/360 (whereby if the starting date is equal to the 31st of the month, it becomes equal to the 30th; if the ending date is equal to the 31st of the month, the ending date becomes the 1st of the following month).
  • 1 bases the year fraction on the actual days divided by the actual days.
  • 2 bases the year fraction on the actual days divided by 360.
  • 3 bases the year fraction on the actual days divided by 365.
  • 4 bases the year fraction on the European method of 30/360 (whereby starting and ending dates that fall on the 31st of the month are made equal to the 30th of the same month).