Pi Day

March 14th is π Day.

The third month and the 14th day
relates to 3.14 which is π to three
significant figures.

Today's challenge is to memorise π to as many digits as you can before it fades completely.


Just for fun play the pi memory game. Students could play the game in groups of three and the winners enter the class final! Two students stand back to back and take it in turns to say the next digit of pi. The person who gets furthest wins!

Though it is not necessary for students to memorise pi these days it is important that they are familiar with it and can use a rough approximation of it to estimate answers to questions. This exercise certainly helps students become familiar with pi but also uses pi as an arbitrary subject of this memory challenge.

Incidently, in the days when memorising pi was important people devised mnemonics such as “How I wish I could calculate pi” where the number of letters in each word represent the first seven digits of pi. Do you know any other mnemonics for remembering pi? Please let us know.


Topics: Starter | Circles | Memory | Multiple Intelligences | Rounding

  • Karen, Klynnjansen@gmail.com
  • I absolutely love many of your problems. I search for open-ended ones & your site usually provides a lot of them! Thanks!
    One suggestion I have is to always have one matching a holiday. I really enjoy incorporating the holidays/current events. I see you have a great upcoming one for Valentine's Day. You provided a fun one on Halloween.
    A few that I would like to see added:
    a Mardi Gras week or at least one on Fat Tuesday
    Super Bowl
    100th Day (or related to the number 100, I realize this varies from school to school, but maybe a week's worth of questions geared toward this celebration)
    St. Patrick's Day
    Keep up the excellent problems for our students.
    Greatly appreciated!
    Veterans Day.
  • Transum,
  • You may have scrolled this far down the page and missed the buttons above that allow you to vary the amount of time pi is visible on the screen. This function adds urgency and excitement to the memorising part of the lesson. You choose the time that would work best for your class. Happy Pi Day!
  • Matthew Zhao, Craigslea State Primary School
  • Starting from last year, I have memorised pi to 100 digits. I purposely finished memorising 100 digits on March 12th. March 13th was for practice and March 14th was for presentation.
  • Will, Carshalton Boys
  • Afterwards, I showed the class the world record holders. They loved it. http://pi-world-ranking-list.com/lists/memo/.
  • Transum,
  • The first time a digit repeats six times in succession in pi is at the 762nd position where you can find six nines in a row. This is known as the Feynman Point.
  • Joke,
  • An opinion without 3.14159265359 is just an onion.
  • Transum,
  • The Welsh mathematician William Jones (1675–1749) introduced the symbol π in 1706, most likely after the Greek word for periphery, which starts with the letter π.
  • Transum,
  • Did you know that you can buy numbers but the most expensive is π.
    Buying π in Jamaica costs £2.00
    Buying π in Trinidad costs £2.40
    Buying π in St Kitts costs £2.15
    These are the π rates of the Caribbean!
  • Transum,
  • How heavy is pi? Where would you go to find its weight?

    "Somewhere over the rainbow…. Weigh a pi".
  • Pranay Pathole, Twitter

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
Click here to enter your comments.

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Online Maths Shop

Laptops In Lessons

Teacher, do your students have access to computers?
Do they have iPads or Laptops in Lessons?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here a concise URL for a version of this page without the comments.


Here is the URL which will take them to a related student activity.


Circle attributes


How does the circumference of a glass compare to the height of the glass? You'll be surprised when you find out.


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Parts of a circle 

Pie In The Sky

Pie In The Sky

Must-watch Pi videos

Cartoon Maths

Pi and Four Fingers

Pi and Four Fingers

In this video mathematician Simon Singh talks about Pi and Maths in The Simpsons cartoon.

The short web address is:


Watch and Learn

Facts About Pi

Facts You Should Know About Pi

Mathematician Presh Talwalkar explains five facts you should know about pi.

The short web address is:


Great Video

A Brief History of Pi

A Brief History of Pi

A video from Simon Clark presenting a deep but accessible account of the history of pi.

The short web address is:


Unexpected places to find Pi

Euler's identity

\( e^{i \pi}+1 = 0 \)

Where \(e\) is Euler's number, the base of natural logarithms (2.718...) and
\(i\) is the imaginary unit, the square root of negative one.

Leibniz Formula

\( \frac{4}{1} - \frac{4}{3} + \frac{4}{5} - \frac{4}{7} \ldots = \pi\)

First discovered by the Indian mathematician Madhava of Sangamagrama in the 14th century
then adapted and published by Gottfried Leibniz around 1676.

Normal Distribution

\( \frac{1}{ \sqrt{2 \pi}}e^{- \frac12 x^2} \)

The normal distribution is the most important continuous distribution in
statistics and the graph is sometimes more commonly referred to as the bell-shaped curve.

Buffon's Needle

\( \frac{2L \times n}{th} = \pi \)

drop \(n\) needles of length \(L\) onto a plane ruled with parallel lines \(t\) units apart.
Count the number of needles, \(h\), that cross lines.

Sum of Reciprocals of Squares

\( \displaystyle \sum_{n = 1}^{\infty} \frac{1}{n^2} = \frac{\pi^2}{6} \)

First posed by Mengoli in 1650 and solved by Euler in 1734 this is known as The Basel problem.


\( \displaystyle\int_{-\infty}^\infty e^{-x^2}dx=\sqrt\pi \)

Even calculus has a use for pi as can be seen in this integration.


\( ( \frac12 )! = \frac{\sqrt{\pi}}{2} \)

I didn't know you could find the factorial of a fraction.

Matt Parker's new book is all about our mistakes and misadventures with maths, geometry and all things numbers. Going from the mundane as to arguments about how many days in a week and the shape of footballs on signs, to famous errors and mistakes like the Space Shuttle disaster, London's walkie talkie building and the Millennium wobbly bridge. He explains how these problems occurred and in the case of some that they had occured in the past and we hadn't learnt from previous experience.

Originally a maths teacher from Australia, Matt Parker now lives in Godalming in a house full of almost every retro video-game console ever made. He is fluent in binary and could write your name in a sequence of noughts and ones in seconds. He loves doing maths and stand-up, often simultaneously.

You can find out more about this book here

Top Scottish teacher Chris Smith was interviewed on the Mr Barton podcast
and talked about his school's amazing Pi Day themes.

Chris Smith's Pi Day Themes

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