Syntax: DATE(Y, M, D)
Y = year
M = month
D = day
DATE returns the date value corresponding to year Y+1900, month M, and date D. Y must be in the range 0 to 199 (representing 1900-2099). The date value is an integer equal to the number of days since December 31, 1899, with the addition of an imaginary day, February 29, 1900, to maintain compatibility with other spreadsheets which mistakenly assume that 1900 was a leap year.
DATE(66, 4, 6) = 24203, April 6, 1966
DATE(366) = Error! wrong number or arguments
Excel function: DATE