# The Infinite Appeal of Pi Day

For all of our readers who are engineers, mathematicians, or simply have an affinity for the constant appeal of Pi, then this day is for you. March 14th is designated as Pi Day.

Pi, as we all learned in school (and are reminded every March 14, on Pi Day), is denoted by the Greek letter π. As many of us learned in school, Pi, is defined as the ratio of a circle’s circumference to its diameter. It is the English spelling of the Greek letter and is pronounced in English as “pie.” Its constant value is used in math that represents the ratio of a circumference of a circle to its diameter. Pi is an irrational number, which means that it is a real number that cannot be expressed by a simple fraction. Computers have calculated it out past 22 trillion digits and longer 3.141592653589793238462643383279502…, going on forever, infinity.

While Pi is an infinite number, you usually see it shortened to two decimal points—3.14. That’s why March 14 (3rd month, 14th day) is the official Pi Day! Today, many people who celebrate Pi Day also feast on a baked pie, sometimes even pizza pie. Pie for Pi.

#### How We Use Pi Today

So, how doesΠ=3.141592 6535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679….. fit into today’s world?

It does, in fact, in many ways. The mathematical constant Pi has a big role in virtually every industry. Take aerospace for example. Engineers in the aerospace industry use Pi for what is known as actuators. Actuators control the flaps that move on aircraft wings and tails or the parts that open and close valves on jet engines. Controllers send signals to electric motors, telling them how fast they need to spin to make the actuators move.

NASA Engineers use Pi to put spacecraft into orbit around other planets. To do this, they have to slow down the spacecraft just enough and at exactly the right time for it to get pulled into orbit by the planet’s gravity. In the search for planets outside of our solar system, Pi is used in the equations that would help us characterize these foreign planets. These exoplanets are characterized by their density, which gives us an idea if a planet is mostly made of gas or rocks and the formula for density just happens to have pi in it.

The constant is also used in various industries. These include, but are not limited to:

Whatever your engineering or mathematical preferences are, enjoy Pi Day, especially if it includes a “pie” for pi.

#### Therese Snow

DELMIA Digital Marketing