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:

## Example Formula

```
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 \(31.4159265cm\).

## Example Database

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.

### View and Duplicate Database

### “Formula (Num)” Property Formula

```
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:**

### “Pretty Formula” Property Formula

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

This formula:

- Intakes the output of the previous formula
- Rounds it to the nearest hundredth (i.e. two decimal places)
- Converts the resulting number to a String
- 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:**