March 14 is a very special day to celebrate a very special number: pi.

If it’s been approximately forever since you took geometry, here’s a quick refresh: Take the circumference of a circle (aka its perimeter) and divide it by the diameter (a straight line through the center). The answer equals pi. This number, represented by the symbol π, begins with 3.14 and the decimals go on infinitely without patterns and without ever repeating.

Math lovers worldwide celebrate Pi Day on 3/14 every year because it’s a terrific excuse to eat pie and get kids excited about math. Here are some fun things you can do.

Calculate pi

Let’s start with the basics. Grab a bunch of round objects in different sizes: plates, takeout containers, drinking glasses, whatever you have on hand. Wrap a measuring tape around the circle to measure its circumference. Then measure across the center for the diameter.

Kids will be amazed that the ratio is always pi, no matter how big or little the circle. The more accurately you measure, the closer your answer will be to 3.14. Extra credit if you do the long division by hand.

Host a pie-eating party

Feast on pi — that is, pizza pi, chicken pot pi and shepherd’s pi. For dessert, judge a pi contest. Apple pi, cherry pi, banana cream pi, key lime pi — which one is your favorite? While pi is infinite, time is not, so don’t be too proud to use store-bought pies.

Bonus: Cut the pies along the diameter into equal wedges so you can enjoy some delicious fraction concepts, too.

Hold a pi recitation contest

Here’s a completely irrational party trick: See how many digits of pi you can memorize. The Guinness World Record holder, Rajveer Meena, memorized pi to 70,000 decimal places. It took him nearly 10 hours to recite all those digits.

Make a pi necklace

You’ll need a shoelace and pony beads for this easy, pi-themed craft. Write or print out digits of pi for your child to see.

Here’s a few to get you started: 3.1415926535 8979323846 2643383279 5028841971

String three beads of one color to represent the first digit of pi, then one bead of another color, then four beads of another color. Keep going as long as your shoelace can hold.

This activity is great for little hands to practice fine motor skills and numbers. Alternatively, you can use Unifix Cubes, Cuisenaire rods or Lego blocks to represent each digit.

It’s also Einstein’s birthday!

How appropriate is it that Albert Einstein was born on March 14? This year would have been the famed theoretical physicist’s 143rd birthday.