Friday the 13th

• The 13th day of a month is more likely to fall on a Friday than on any other day.
  
• In each 400-year cycle of the Gregorian calendar, 170 years have one Friday the 13th, 171 have two, and 59 have three.
  
• It is impossible to have a year with no Friday the 13th or a year with four or more Fridays the 13th.
  
• When there are three Fridays the 13th in a year, they occur in February, March and November except in leap years.
  
• In leap years, they occur in January, April and July.
  
• When there is only one Friday the 13th in a year, it falls either in May, June, August or October.