"% of" in the Math Input box

Let’s say I am making an activity about percentages, and I want students to enter an answer like “50%” into a math input box. When you enter the percent symbol into the math input, it immediately becomes “% of”. If you try to delete the “of” part, it deletes everything.

I know the suffix sink can get around this because it prevents students from entering anything that isn’t a number. But is there a way to allow students to enter “%” as part of the answer and not have the input box immediately tack on “of”? I really want them to get in the habit of labeling their answer with appropriate units or symbols rather than having the suffix box do it for them. Would I just have to go for the text input instead?

My best solution would be to add
initialLatex: "\%"
and then add a note telling students that if they accidentally delete the percent sign, they should copy and post \% into the note.