100

The year 100 started on Wednesday, January 1, and ended on Thursday, December 31. It was a leap year (in the Julian calendar, although it would not have been a leap year in the proleptic Gregorian calendar). Also, it was the last year of the 1st century, and the first three-digit year.

Calendar with holidays
Holidays:
 * New Year's Day: Wednesday, January 1
 * Leap Day: Saturday, February 29
 * Halloween: Saturday, October 31
 * New Year's Eve: Thursday, December 31