DATE(year,month,day)
year: year of date
month: month of year
day: day of month
The DATE function creates date serial values. 1-Jan-1900 is serial value 1, 2-Jan-1900 is serial value 2, and so on. For compatibility reasons, a serial value is reserved for the non-existing date 29-Feb-1900.
If month or day is less than 1 or too big, then the year and/or month will be adjusted. For spreadsheets created with the Mac version of Excel, serial 1 is 1-Jan-1904.
This function is Excel compatible.