Pi day: How to memorize the world's most famous irrational number

From images and stories to poems and songs, there are numerous ways to sharpen your memory and improve your retention span

John Badman/AP Photo/The Telegraph
Students celebrated Pi day by doing a few pie activities. Pi is the ratio of a circle's circumference to its diameter. Pi has been calculated to more than one trillion digits past its decimal so students competed by reciting as many digits as they could. There was also a pie eating contest and the three teachers whose students raised the most money for 5A's Animal Shelter got pies in the face.

If you tend to write your date in a month-date format (like we do in the US) then Friday is a reason to celebrate. 

It's 3/14. Replace the slash with a decimal point and you have 3.14 – the beginning three digits of the world's most famous number that is both irrational and transcendental. Today is Pi Day, which just so happens to coincide with the birthday of Albert Einstein.

Calculated as the ratio of the circumference of a circle to its diameter, the digits of pi do not repeat themselves and continue forever.

And there are people out there who actually try to memorize the numbers. Yes, they actually do.

The current world record for memorizing pi is held by Chao Lu, who recited the 67,890 places of pi in 24 hours 4 seconds back in 2005.

Describing his memorization technique, Bruce Bower 
of Science News wrote in an article:  "Chao Lu described generating mental images for number pairs from 00 to 99, such as classroom for 94 and stones for 17. From these cues he created stories. 

For lists of 15 to 75 numbers, Chao Lu reported constructing five-image stories. Fourth and fifth images took him longer to study than preceding images did, consistent with having to integrate later images into a pre-existing story line. Chao Lu took longest to retrieve initial images, which cued recall of later images. "

Images and stories are considered efficient mnemonic techniques to boost one's retention power.

Project HappyChild, non-profit organization based in the UK talks about "The Linking Technique" where items that need to be remembered are linked in the form of a story. "The technique relies on making a vivid story that not only helps you remember each of the items, but also the order in which they appear," according to the website.

A group of scientists from Purdue University emphasized the importance of "retrieval practice technique" to remember things. In an experiment they conducted, students were divided into two groups – one group chose elaborative studying technique where they used "concept maps," diagrams used to understand the texts. The other group read their texts and put them away. Both the groups then returned a week later.

"The students answered questions about the specific concepts they learned as well as inference questions asking them to draw connections between things that weren't explicitly stated in the material. On both measures of meaningful learning, practicing retrieval continued to produce better learning than elaborative studying," said Jeffrey D. Karpicke, an assistant professor of psychological sciences who studies learning and memory.

In "Your Memory: How It Works and How to Improve It," author Kenneth L. Higbee talks about effective visualization techniques that can help remember things. "Three factors that help to make your visual associations effective —interaction, vividness, and bizarreness," he writes.

Many researchers have also illustrated the importance of color on memory. In fact "the choice of colours and the manipulative aspects can, however, influence the extent to which colours can influence human memory performance," states one paper.

In addition to these techniques, there are numerous pi songs and poems to make you good at piphilology (study of mnemonic techniques to remember pi). 

And for those who write in the day/month date format, note that Pi Approximation Day is observed on 7/22, a fraction that, while not quite as precise, is a good deal easier to remember.

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