# pi

Learn how to use the mathematical constant pi in Notion formulas.

The mathematical constant

*pi*($π$

) equals (roughly) `3.1415926559`

.1

pi

$π$

is the **ratio between the circumference and diameter of a circle.**This ratio is shared by*all*circles, no matter the size.

$π$

can be used to calculate the circumference and area of a circle, volume and surface area of a sphere, and more.You can learn more about

$π$

here:1

pi * 10

The above formula will calculate the circumference of a circle with a

**diameter**of 10cm. It uses the simple equation$πd$

, where $d$

is the diameter of the circle.In this case, the circumference would be approximately

$31.4159265cm$

.In this example database, the

**Formula (num)**property calculates the area of a circle with a given radius, set in the**Circle Radius (cm)**property.1

pi * prop("Circle Radius (cm)") ^ 2

The formula to calculate the area inside a circle is

$πr^2$

. We can create this equation in a Notion formula using the code above:`pi`

is the Notion constant for$π$`prop("Circle Radius (cm)")`

uses the`prop()`

function to pull in the value of the`Circle Radius (cm)`

Number property`^ 2`

squares the radius of the circle

**Other formula components used in this example:**

1

format(round(prop("Formula (num)") * 100) / 100) + "cm²"

This formula:

- 1.Intakes the output of the previous formula
- 2.Rounds it to the nearest hundredth (i.e. two decimal places)
- 3.Converts the resulting number to a String
- 4.Appends “cm²”

Note that Notion formulas do not support text formatting, so I’m using the actual

`²`

symbol. You can find this symbol here:To round the decimal to two decimal places, I use the following trick:

1

round(prop("Formula (num)")*100)/100

Notion’s built-in

`round()`

function only rounds numbers to the nearest whole integer. But this trick will output a rounded number to two decimals places instead. Learn more about this trick in the round function reference.**Other formula components used in this example:**

My name is Thomas Frank, and I'm a Notion-certified writer, YouTuber, and template creator. I've been using Notion since 2018 to organize my personal life and to run my business and YouTube channel. In addition to this formula reference, I've created a free Notion course for beginners and several productivity-focused Notion templates. If you'd like to connect, follow me on Twitter.