This fact is actually in reference to the Monday we just passed, January 12th. On that day in 1665, Pierre de Fermat passed away. Fermat, of course, is known for the infamous conjecture “Fermat’s last theorem.”
In this conjecture, Fermat insisted that xn + yn = zn has no solutions when x, y, and z are non-zero integers and n > 2. The theorem was found in the margins of another math text that Fermat had been studying, and was published by his son in 1670.
Fermat’s Last Theorem has been a subject of intrigue for mathematicians and non-mathematicians alike for many years because it took more than three centuries to find a true proof. British mathematician Andrew Wiles finally proved the conjecture in 1994, but he used tools that were not invented until long after Fermat’s death. It is likely that his original proof in the 1600s was incorrect.
The theorem is known widely, and has even been referenced by pop-culture by The Simpsons and Star Trek: The Next Generation. It remains a fascinating piece of mathematical history to this day.