Craft.io's Formula fields enable you to create a calculated score field from your choice of numerical fields.

To create a Formula field, go to Workspace settings -> Custom fields, click on the 'Add' button and select 'Formula' from the menu.

Note: Only users with Admin permission type can create Custom fields.

Then, you will need to create the score by selecting the relevant fields from list.

You can only select "Number" fields or "Single selection" field with a numerical value.

For each field that is included in the formula, you will need to define the weight (on a scale of 0-100%), as well as set the algebraic relation between the fields (addition, subtraction etc.).

The Formula field will not be displayed at the Item properties panel as it is not an editable field. Instead, it will be listed with all other fields to select for 'Table View' columns:
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Craft.io’s formulas play an important part in the prioritization process.
With formulas, you can generate prioritization scores based on several numeral fields. A simple example of a formula is: Score = Value / Effort, where Value and Effort are numerical fields.

However, when product managers need to input data into these fields, they need a specific number, say “5” or “8”. This might create two problems: first, a product manager may not have a precise number in mind (“should I fill ‘5’ or ‘6’?”);
Second, they might be manipulating the numbers a bit to reach their preferred score (don’t we all do that from time to time?).

To solve these problems, we have developed the ability to add selection fields to formulas: for the example above, you can define the Value and Effort fields as T-Shirt Size value: S, M, L & XL.
In this case, the product manager can simply fill “Value = L” and “Effort = M”, abandoning the guessing game regarding which exact number they should use.
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But how does the calculation happen? When you define those fields, you apply a numerical value to each option (e.g. S = 20, M = 40, etc.); these values will be used when the formula is calculated. However, when a product manager inputs data into those fields, they will only see the abstraction layer (S, M, etc.), without the numerical values.