It’s Leap Year Day!

Common knowledgcredo's article leap yeare says we enjoy this extra day every four years, but is that really the frequency of February 29? Two online resources from the MIT Libraries answer this question and highlight the breadth of information they offer the MIT community.

Credo, a vast array of online encyclopedias, offers quick background on the subject of Leap Year. Besides confirming only century years divisible by four “leap,” you can also learn the term is first written in “English medieval encyclopedia On the Properties of Things (1398), translated by John Trevisa from the 12th-century Latin original by Bartholomew the Englishman.”[i]

MathSciNet, a major international math database, provides more leap year math. To quote:

“N is called a leap year if ∑∞k=1(−1)k+1(a1a2⋯ak|N)=1, where (xy)=1 if x divides y and 0 otherwise.”[ii]

Leap into this day and the MIT Libraries!


[i] Leap year. (2004). In Word histories and mysteries. Boston, MA: Houghton Mifflin. Retrieved from