The mathematically-minded will recognize a special pattern in today’s date— 11/23— the first four numbers of the famed Fibonacci sequence, in which the next number is determined by adding the previous two: 1, 1, 2, 3, 5, 8, 13, 21 and so on. It is named for Leonardo of Pisa (c. 1170 – c. 1240–50), known as Fibonacci.

Fibonacci numbers appear widely in nature as in the branching of trees and the sprouts on a pineapple. And they occur so often in mathematics that there is an entire journal dedicated to their study, the Fibonacci Quarterly.