How to write expression in such case-2

Hi, 

I was playing with expression.

Suddenly I think of something and wanted to see if I can do that.

So generally we take a text layer and write something and then convert it into mathematics. I took a text layer, write an alphabet/word then math round, slider control, and wrote expression and I was happy. All was okay. But suddenly I think what if I want a space between the digit and the percentage? What I have to do then? I was very confident that if I write two alphabets and put a space between them like ‘a b’ instead of a single word or alphabet or if I write ‘ab’ and then put a space after them, then I have space between the digit and percentage. Guess what? Like always it didn’t work. So What I should do or write in coding if I want a space between the digit and ‘%”?