Under "Tools - Date Calculator" The software does not take in account Leap Year calculations. A number of things have to be right for the error to present itself. The year of death must be during Leap Year, the death must be in March, the month of birth must be after the month of death. My Father met all the requirements, they are. birth 25 May 1907, death 13 March 1984. The FTM answer is 76-9-16, it should be 76-9-17. This error is small and is probably inconsequential but it is an error.