March 14 was Pi Day. Literally. It happens just once every hundred years.

Why?

Because March 14, 2015 is 3.14.15 and at 9:26 and 53 seconds, the moment can be represented as follows: 3.141592653, the first 10 digits of pi.

DJ Patil, chief data scientist of the US and deputy chief technology officer at the White House Office of Science & Technology Policy, recorded this in an excellent blog. (Click here to read it).

He goes on to explain why pi, a number that’s represented by the symbol π, is so important. “It’s literally one of the foundations of our society,” he writes, “In fact, every civilization had to figure out pi. The Greeks, Ancient China, India, Egypt, the Babylonians, all worked hard to calculate it as precisely as they could.”

Archimedes figured out a way to calculate its value more than 2,000 years ago.

Mr Patil offers some “simple” examples of the use of pi in our daily lives: to calculate the amount of cloth needed to cover a round picnic table, we’d multiply pi by the area of the table. The amount of air in a basketball? (4/3) x pi x radius-cubed.

And then he sets a brain teaser that’s beyond me but to which he will be tweeting the answer today: “Imagine you have a rope snug all the way around the equator of the Earth. Now you need to add some rope so that the rope is 2 inches above the ground all the way around. How much rope do you need to add?”