Pi Day was celebrated on March 14th (3.14) around the world. Pi (Greek letter "π") is the symbol used in mathematics to represent a constant - the ratio of the circumference of a circle to its diameter - which is approximately 3.14159. Pi has been calculated to over one trillion digits beyond its decimal point. As an irrational and transcendental number, it will continue infinitely without repetition or pattern. While only a handful of digits are needed for typical calculations, Pi's infinite nature makes it a fun challenge to memorize, and to computationally calculate more and more digits.

Coincidentally, March 14 is also the birthday of Albert Einstein. The famous German scientist would have turned 138 years old this month. Here are some known and relatively unknown facts about Al.

*    He was under FBI surveillance for a rather long time. - Not long after Einstein moved to the U.S., FBI boss J. Edgar Hoover had agents begin spying on him. Fearing that the left-wing, pacifist, intellectual Einstein could be some kind of threat to the establishment or even a Soviet spy.

*    He developed his most important theories while working a rather tedious day job. - Just after the turn-of-the-century, a twenty-something Einstein needed a steady income and took a job as a patent clerk in a Swiss office.

*    He couldn't get a job in academia for almost a decade. - The reason the young Einstein settled for that patent clerk job is that no academic institution would hire him. Although his professors knew him to be brilliant, they also saw him as rebellious and unruly, thus refusing to recommend him for various positions.

*    He rarely visited a lab. - Although he developed theories that obliterated the boundaries of science and is himself perhaps the most famous scientist of all time, he worked things out in his head or on paper at his desk, hardly ever visiting a laboratory.

*    His brain was stolen. - After Einstein died, the pathologist who did his autopsy took his brain without permission.

*    His speech development during childhood was significantly delayed. - Einstein didn't begin speaking until the age of four.

*    He was born with an alarmingly enormous head.

*    He really didn't like socks, and usually didn't wear them.

*    He never actually failed math. -
This is a popular "fact" often promoted on the internet, perhaps in an attempt to humanize Einstein's genius. However, it is simply not true. Overall, Einstein was an average student, but math was one area where he excelled, unsurprisingly.

*    He did, however, fail his university entrance exam. - In 1895, a 16-year-old Einstein took the entrance exam for the Swiss Federal Polytechnic, a science, technology, engineering and mathematics school. While he had exceptional scores in physics and math, his other scores weren't good enough and he failed the exam as a whole.

*    He was a great musician. - If the whole "genius" thing didn't work out, Einstein could have become a working violinist. His mother played piano so he had the love of music instilled in him via violin lessons at the young age of five.

*    He could have been the President of Israel. - When Israel's first president, Chaim Weizmann, died, Einstein was offered the position, but he declined.

*    He married his cousin. - After Einstein divorced his first wife, Mileva Maric, he married his cousin, Elsa Lowenthal.