The Ohio State University at Newark

VIDEO: Ohio State Newark Celebrates Pi Day by Measuring the Great Circle

NEWARK, Ohio, March 14, 2016 – It may simply be March 14 to you, but to math enthusiasts, today is a special today. The date 3-14 is known as Pi Day. The number π or 3.14… is the ratio of circumference to diameter in a circle. The Ohio State University at Newark Assistant Professor of Mathematics Niles Johnson decided to celebrate the occasion by measuring the biggest circle he could think of - the Great Circle at the Newark Earthworks.

“I was thinking about what I could do for Pi Day, and it occurred to me that we have this giant circle in Licking County that is just waiting to be measured,” said Johnson. Physicists in San Francisco first celebrated Pi Day in 1988. Congress officially recognized Pi Day in 2009. Students admitted to the Massachusetts Institute of Technology are notified of their admission on Pi Day, and the town of Princeton, New Jersey, combines Pi Day with the birthday of Albert Einstein.

"We in LickingCounty can celebrate Pi Day in an earthen enclosure built nearly two millennia ago by the very culture that made such a discovery. In most places, people celebrate Pi Day by eating pies. We can celebrate Pi Day by measuring the circumference and diameter of the Great Circle. In this way, we measure the number pi itself, much as native cultures must have understood it," said Johnson.

Johnson organized an event for students, faculty, staff and their children on March 12 at the Great Circle. About 50 people participated in the event. Ohio State Newark students from Johnson’s math classes volunteered to help during the event.

The goal was to discover the area enclosed by the Great Circle Earthworks using pi. The Great Circle was built approximately 2000 years ago by ancestors of today's American Indians who made up what archaeologists have named the Hopewell Culture. Johnson had groups of children work in teams to measure the circle, and then use the meaning of pi to derive the measurement of that number. The collaborative outreach event was organized by Ohio State Newark and the Newark Earthworks Center.

“We had four groups measure the circle, two measured for circumference, two measured for diameter. We got a circumference measurement of 3,372.5 feet and a diameter measurement of 1,071.5 feet,” said Johnson. “After dividing, we got a pi measurement of 3.147456. The actual value of pi is 3.141592653. So, our percent error was 00.18%, which is less than .2%.””

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