"Shortly after 2:29 p.m. EDT today, the U.S. population clock will reach a milestone that is very meaningful to mathematical statisticians: It will show there are 314,159,265 residents, or pi (3.14159265) times 100 million," the bureau said in a release.
Pi is a mathematical constant that is the ratio of a circle's circumference to its diameter.
"This is a once in many generations event ... so go out and celebrate this American pi," Census Bureau Chief Demographer Howard Hogan said.
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