February 29 is a date that usually occurs every four years, and is called leap day. This day is added to the calendar in leap years as a corrective measure, because the Earth does not orbit the sun in precisely 365 days. The Gregorian calendar is a modification of the Julian calendar first used by the Romans.
For example, in the formula DATE( 2008, 5, -15), the DATE function returns a datetime value equivalent to April 15th of 2008, because 15 days are subtracted from the beginning of May 2008 yielding a value of April 2008.
For example, Texas residents were given SSNs with the first three numbers in the range of 449-467. However, to help prevent identity theft and provide numbering flexibility, SSNs are now assigned on a random basis to new SSN recipients. Current SSN holders will not have their number affected by the new random system. You can learn more about how legacy SSNs were assigned on the basis of state by visiting here : https://secure.ssa.gov/poms.nsf/0/b5743fd0e02b42578525754c0005a686. http://ssa-custhelp.ssa.gov/app/answers/detail/a_id/425.