# pi

The mathematical constant pi ($$π$$) equals (roughly) 3.1415926559.

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:

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.

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:

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:

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: