World Coins

March 14 is Pi Day: yep, there’s a coin for that!

The first 1 million digits of Pi appear — in tiny detail — on the reverse of a Prooflike .999 fine silver $2 coin issued in 2014.

Images courtesy of the Helvetic Mint.

Math’s most famous figure, Pi, is celebrated throughout the world on March 14 (3/14 in the American style) and the 2015 celebration is particularly special.

Add the year to the naming convention, and you get 3/14/15, the first five digits of the mathematical constant, the ratio of a circle’s circumference to its diameter, which approximately equals 3.14159. 

Pi is also celebrated on a coin.

In 2014, the Helvetic Mint issued a Prooflike .999 fine silver $2 coin for Niue that features the first 1 million digits of Pi. The digits are encoded on an 11-millimeter-square “nanojem,” which under extreme magnification can be read. And that is only part of Pi, as some 1 trillion digits of the never-ending decimal representation have been discovered.

Pi never settles into a permanent repeating pattern. In mathematical terminology, it is an “irrational” and a “transcendental” number, it never repeats and never ends. It has been represented by the Greek letter pronounced "Pi" since the mid-18th century. 

The earliest written approximations of Pi are found in Egypt and Babylon, both within one percent of the true value. In Babylon, a clay tablet dated 1900 to 1600 B.C. has a geometrical statement of Pi.

The first recorded algorithm for rigorously calculating the value of Pi was a geometrical approach using polygons, devised around 250 B.C. by Greek mathematician Archimedes.

The Niue coin weighs 50 grams, measures 50 millimeters in diameter and was limited to a mintage of 500 coins. 

Like the elusive search for additional digits to Pi, the search for the coin in the secondary market may prove elusive.

More from

Three-coin 2015 March of Dimes Special Silver Set goes on sale May 4 from U.S. Mint

$60,000 gold coin is lost at ANA National Money Show, found and returned within hours

2,500-year-old gold and silver coins found in U.S. college's library

1916-D ‘Mercury’ dime brings $94,000: Key graded MS-66 full bands leads Heritage’s PNG show auction

Ronald Reagan dollar coin design proposals released by U.S. Mint

Please sign in or join to share your thoughts on this story.

Keep up with all of's news and insights by signing up for our free eNewslettersliking us on Facebook, and following us on Twitter. We're also on Instagram!

Community Comments