Format measure as percentage (number, not string)

Hello,

I would like to add a measure that is formatted as a percentage and is still a number (not text). I tried this formula:

=FormatNumber(Actual;"#,##0.0[%]%")
This returns the correct format (42.1%), but it is now a text because of the %-sign.

Since it is a text, I can't use the ToNumber function either. I know that I can format the column manually when I add the measure to a table, but I would like to format it completely in the function for several reasons.

Can anyone please help me?