Formulas can be used in data view reports and in computed custom fields. 

Data Views with Formulas

To add a formula to a data view report, on the Edit Field screen, go to the Formula tab to enter your formula into the formula editor.

Custom Fields with Formulas

If you wish to add a formula into a custom fiel, then follow these steps:

1. Go to the Management screen and click the Custom Fields button.
2. On the Custom Fields screen, choose the entity that you would like to add the custom field.
3. Click the '+' toolbar button to add a custom field.
4. On the New Custom Field screen, set the type to be Computed. This allows you to enter a formula.  

Using Auto Complete in the Formula Editor

In the formula editor, as you type, a popup window will display predicative text that shows you the operators, functions, entities and fields that are available within formulas.  You can choose items from the popup window to quickly insert them into your formula.

Tip: Press Ctrl + Space on your keyboard to get help on what operators, functions, entities and fields are available.

Tip: Use your mouse to click on a function in your formula, and then press Ctrl + Space to see a description including arguments and return value for the function. 

Using Find and Replace in the Formula Editor

In the formula editor, press Ctrl + F to display the find and replace features of the formula editor.