Gentleman's Diary or The Mathematical Repository was (a supplement to) an almanac published at the end of the 18th century in England, including mathematical problems.

The supplement was also known as: "The mathematical repository: an almanack" or "A Collection of mathematical problems and ænigmas".

• Serial Publication: Annual 5 v. tables. 16 cm
• Publisher: Printed for J. Fuller (1741–1745)
• Place of publication: London, England
• Continued by: The Ladies' Diary and then The Lady's and Gentleman's Diary
• Language: English
• OCLC: 5535685
• Journal began: 1741 Ceased publication: 1800
• Libraries worldwide that own item: University of Illinois, University of Oklahoma