There were 540 days whose date was 13. Of these 78 fell on a Friday. These were (in international notation):
13/05/55,
13/01/56, 13/04/56, 13/07/56, 13/09/57, 13/12/57, 13/06/58, 13/02/59, 13/03/59, 13/11/59, 13/05/60,
13/01/61, 13/10/61, 13/04/62, 13/07/62, 13/09/63, 13/12/63, 13/03/64, 13/11/64, 13/08/65,
13/05/66, 13/01/67, 13/10/67, 13/09/68, 13/12/68, 13/06/69, 13/02/70, 13/03/70, 13/11/70,
13/08/71, 13/10/72, 13/04/73, 13/07/73, 13/09/74, 13/12/74, 13/06/75,
13/02/76, 13/08/76, 13/05/77, 13/01/78, 13/10/78, 13/04/79, 13/07/79, 13/06/80,
13/02/81, 13/03/81, 13/11/81, 13/08/82, 13/05/83, 13/01/84, 13/04/84, 13/07/84, 13/09/85, 13/12/85,
13/06/86, 13/02/87, 13/03/87, 13/11/87, 13/05/88, 13/01/89, 13/10/89, 13/04/90, 13/07/90,
13/09/91, 13/12/91, 13/03/92, 13/11/92, 13/08/93, 13/05/94, 13/01/95, 13/10/95,
13/09/96, 13/12/96, 13/06/97, 13/02/98, 13/03/98, 13/11/98, 13/08/99.
26 Fridays
The conventional conversion of April 13th 1994 into Roman numerals is April-XIII-MCMXCIV whether or not the Romans themselves did it this way is open to question.
There are 52 weeks in a year. The answer is 52 Fridays normally, but since the year begins and ends on a Friday, there are 53 Fridays in 2010.
The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.
The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.The 13th of October.
February, March and November.
Friday the 13th's Are unlucky!
13th June 1955 was a Monday.
August 13th, 1994 fell on a Saturday.
February 13th, 1994 fell on a Sunday.
Monday, June 13, 1955
June 13th 1955 was a Monday.
November 13th, 1955 fell on a Sunday.
It was a Thursday.
Wednesday
The 6th, 13th, 20th and 27th of October 2000 were all Fridays.
13th December 1994 was a Tuesday.