In Numbers 13.2 for Mac I am subtracting dates between two cells formatted in dates and the software automatically formatted the resulting cell as a duration in days. When I then multiply this cell (days units) by another ($/day) the result comes ou

In your multiplication, you may want to convert the duration into a plain number with DUR2DAYS or another appropriate conversion function.

I tried this problem in Numbers Version 13.1 and the result was a plain number without using DUR2DAYS if the $/day was formatted as currency or had the currency symbol in it. It is surprising that this would change in version 13.2 but I cannot test it. I just realized I am locked at 13.1 until I upgrade my OS, which I cannot do because my computers are incompatible. Oh well.

Whether needed or not, using DUR2DAYS is good practice because otherwise the result of the multiplication will change if the duration unit is changed to something other than days.

Without using DUR2DAYS here is what I see in Numbers 13.2.

You can get the result you want if you format the Rate/Day as Currency and Result as Currency.

But not if you leave Rate/Day as Automatic or Number.

Best practice, I would argue, is to be sure by using DUR2DAYS or one of its cousins to convert the Duration to a decimal for further calculations.

SG

Same results as 13.1.

Here is one more result from not using DUR2DAYS (same duration, different results):