AutomatorWP – Calculator add-on adds the calculate formula action to let you perform mathematical calculations on tags and use the result in your automations!
You can perform sums, subtractions, multiplications, divisions and even apply functions such as abs, sin, cos among others as explained here.
In addition, Calculator includes function tags to let you perform mathematical calculations directly in fields as explained here.
You can view the list of symbols supported here.
Also, you can check the automations samples page where you can see some samples of the possibilities of this add-on.