This Saturday, March 14, 2026 is Pi Day. The first three digits of pi are 3.14, making March 14 (3/14/2026) the perfect day to celebrate this mathematical constant.

Pi, often represented by the mathematical symbol shown to the right, represents the ratio of a circle's circumference to its diameter.

In its simplest terms, if it takes you 1 minute to walk across a circle, it will take 3 minutes and 9 seconds to walk around the same circle. That's the circumference (3.14) divided by the diameter (1.0)

In 2009, the U.S. House of Representatives passed House Resolution 224, a resolution supporting the designation of Pi Day, recognizing the importance of the National Science Foundation's math and science programs, and encouraging schools to celebrate with activities focused on pi and the study of math.

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Pi was discovered through ancient observations that the ratio of a circle's circumference to its diameter is a constant, approximately 3.14. Early civilizations like the Babylonians and Egyptians estimated this value by measuring physical objects.

. Key details on the discovery of Pi:

• Initial Discovery: Ancient Babylonians (around 1900 - 1600 BCE) noticed that a circle's circumference is roughly 3 times its diameter, with tablets suggesting a value of 3.125.
• Egyptian Estimation: The Rhind Papyrus (circa 1650 BC) indicates the Egyptians approximated to be approximately 3.16.
• Archimedes' Method: Archimedes of Syracuse (c. 250 BC) revolutionized this by using polygons and a method of exhaustion, drawing regular polygons with 96 sides inside and outside a circle to trap the value of pi between 3^10/71 and 3^1/7.
• The Symbol for pi was proposed by Welsh mathematician William Jones who first used the Greek letter in 1706 to represent this constant.
• Modern Calculation: Following Archimedes, mathematicians used increasingly complex polygons and later infinite series (via calculus) to calculate to thousands, and now trillions, of digits.

The discovery was not made by one person, but rather developed over millennia as a fundamental mathematical constant, representing how many times a circle's diameter fits around its circumference.

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Here is PI to 100 decimal points. Using this number, you can calculate the distance from the earth to the moon to less than one millimeter.

     3.141592653 5897932384626 4338327950288 4197169399375 1058209749445 9230781640628 6208998628034 8253421170679