DATE
Category: DateTime Function.
Description: Returns a sequential serial number that represents a particular date.
Syntax: DATE(year,month,day)
Year: A number that may include from one to four digits.
If the year is between 0 (zero) and 1899 (inclusive), this value is added to 1900 to calculate the year.
If the year is between 1900 and 9999 (inclusive), this value is used as the year.
If the year is less than 0 or is 10000 or greater, the #NUM! error is returned.
Month: A positive or negative integer representing the month of the year.
If the month is greater than 12, this number is added to the first month in the year specified.
If the month is less than 1, this value plus 1 is subtracted from the first month in the year specified.
Day: A positive or negative integer representing the day of the month.
If the day is greater than the number of days in the month specified, this number of days is added to the first day in the month.
If the day is less than 1, this value plus 1 is subtracted from the first day of the month specified.