Calculation with items that use Units of Measurement ("%" or "°C")

[rossko57]

Should help

Working with Number:Temperature Items in rules

openHAB provides Quantity Type features, which can seem baffling. On top of that, Temperature type Quantities have a few quirks all of their own. These notes intend to guide the rules author. I’ve shown work examples in DSL rules language, see below for other scripts examples. All have similar features, if different syntax. Knowing what can be done is half the battle. What is a Quantity Type? Simply, Item states and rule variables may contain Quantities - that just means a number AND a unit …

@Cplant

Is there a way to get rid of the strings during the calculation?

Try not to do that; work with the units.