[Feature Request] Math operations on custom fields using workflows

Description

Using custom fields, you sometimes want to do some calculations on numbers. If you scan your tank receipt, you might want to calculate the monthly (yearly, ...) amount of filling up the car. When having multiple unpaid invoices, you want to add up the total. If you have a binary system based permission system for documents, you might want to subtract group based permission levels to recalculate the new level of missing permissions required to enable the workflow's next step.

I think that these calculations could be done within a workflow action by adding math operators (+, -, *, /, %).
Make the result reusable (=set result as new value).

Other

_No response_