ORIGINAL. AUTHENTIC. Although there are other mathematics calendars by the same name, this is the original mathematics calendar first introduced to the public in 1979. Each problem's answer is designed to come out to the date on which it appears. In addition, every month presents current or popular math topics or ideas. It's more than a calendar, but instead, a mathematical calendar magazine. The Mathematics Calendar 2019 will be Pappas' farewell mathematics calendar. - A retrospective of problems spanning 38 years. Many past topics will be revisited, expanded and updated to reflect the ever evolving changes in the world of mathematics. As it has for nearly four decades, The Mathematics Calendar 2019 will inform, entertain, challenge and enrich. It will probably become collectible.--Theoni Pappas