**There is a very special thing, when the circumference divided by the diameter is always the same number, no matter how big or small the circle.** Historians are not sure when or how this number was first discovered, but it has been known in some form since about 4000 years ago.

Mathematicians estimate it by inscribing circles within polygons and appeared in the work of ancient Greek, Babylonian, Chinese and Indian mathematicians. Until 1400, it was defined and valid to 10 decimal places. So the question is **when will people find out its exact value?**

And **the answer: Never!** You see, everyone knows the ratio of a circle’s circumference to its diameter is an irrational number, you can get close to it, but you’ll never reach it no matter what. So to write it as a decimal you would have to write a sequence of digits that starts with 3.14159 and goes on forever! So, instead of trying to write down an infinite number of digits every time, we represent it **with π (Greek letter pi).**

It is a fact that the matter in the universe is nothing compared to the infinite number of digits of pi.

Today, we test the speed of computers by having them calculate pi, and quantum supercomputers are already able to calculate pi to millions of billions of digits. People also competed against each other to see how many digits they could remember and the record for someone remembering more than 67,000 digits. But in scientific applications, most of the time you only need about the first 40 digits. So **what are these scientific applications?**

Any calculation that involves a circle from the volume of a soda can to the orbit of a satellite. And not only circles, it is also used to study curves. Pi helps us understand cyclic or oscillating systems such as clocks, electromagnetic waves and even music.

In statistics, pi is used in the equation for the area under the normal distribution curve to find the distribution of benchmark scores, financial models, or margin of error in scientific results. And yet, pi is also used in molecular physics experiments such as those using large particle accelerators to calculate the trajectories of moving molecules.

And perhaps most impressively, is using pi to measure the density of the entire universe. It is a fact that the matter in the universe is nothing compared to the infinite number of digits of pi.