# What is Pi Day?

Pi Day is celebrated on March 14^{th} (3.14). It is a special day commemorating the mathematics constant pi. The constant pi is used in many branches of mathematics and the sciences. Pi is used in other areas of study that use mathematics content such as trigonometry, geometry, calculus, probability, and statistics. Such areas includes post secondary educational studies in areas such as engineering, social sciences, government, agriculture, architecture, and business.

Pi Day has been celebrated by mathematics enthusiasts since about 2004. It became a nationally recognized day after the United States House of Representatives Committee on Science and Technology submitted House Resolution 224 on March 13, 2009 in support of Pi Day. The House resolution passed by a vote of 391 to 10. Since House Resolution 224, the day has spread internationally. This is an indication that most politicians understand the importance of mathematics and science in education and to ensuring the United States' place as a leader in education, mathematics, science, and technology.

The first six digits of pi are 3.14159. Pi, also known in mathematics as Archimedes’ constant, is an irrational number and a transcendental number. If students of mathematics are not familiar with these definitions, then teachers might let them research the meanings of these two words and give examples. Students might also research the history of pi and the history of the words irrational and transcendental in terms of “who”, “when”, and “how”.

In secondary school and college mathematics, the use of the constant pi is widespread. Pi is used in pre-algebra, trigonometry, calculus, analytic and plane geometry, differential equations, probability, and statistics. Such courses provide a foundation for other higher courses in mathematics, science, engineering, and computer science to build upon.

To celebrate Pi Day appropriately, it is important to engage in meaningful activities and investigations that enhances knowledge of mathematics and the sciences. It should not be just a day of play and eating pie, but a day to engage in mathematical and scientific investigations and/or mathematical competitions centered on knowledge about pi and pi related information. An individual’s creative side might be brought out by applying mathematics or science to art, music, and dance.