Math enthusiasts rejoice: it’s Pi Day.

Pi Day is celebrated each year on March 14 because the date resembles the ratio of a circle’s circumference to its diameter, 3.14 for short.

Professional engineer Jackie Pettway said she uses Pi every day in her work as chief of the navigation division at the U.S. Army Engineer Research and Development Center and as an adjunct engineering instructor for Mississippi State University.

“Within my division, we do all things navigation,” she said. “We do field work, laboratory experiments, physical models and numerical models.”

This includes work involving the expansion of the Panama Canal to the carp invasion in United States’ rivers.

One way Pettway and her team use Pi is measuring the radius of a roller gate used in a dam.

“We have to make sure there’s enough of it there to cover all of the water,” she said. “It’s a cylinder that can be raised and lowered.”

Another way Pi is used by the navigation division is calculating pipe flow.

“When we’re doing our physical models, we need to calculate pipe flow with a continuity equation,” she said. “You have to know that area to know what’s coming through. We do that just about every day.”

When Hurricane Katrina hit New Orleans, there was an issue with pumps failing, and Pettway’s team stepped in to help determine the appropriate size of the pumps and how that would impact the piping.

“We used Pi to calculate the surface area coming through those pipes,” she said.

Pettway said in her division, they build a lot of scale models to test their ideas to make sure they’ll work out in the real world.

Many math lovers pride themselves in memorizing digits in Pi, and Pettway said she used to be one of them.

“I at one point had about 14 digits memorized,” she said. “That was a big thing when I was in college.”

Pettway said usually only four to six significant digits are calculations and engineering classes.