How to hint at how many characters are in an answer? _ _ _ (3)

I'm trying to show how many letters are in a word.

I want to do that with underscore characters. BUT there is no space demarcating the underscore in most fonts. E.g., how many characters is this? ____

One solution is to use a common web font that does have space, although I'm open to other suggestions. (I'd prefer not to have to put in dummy spaces). Robo Slab happens to do this nicely, but Not sure how common it is.

But I'd also love to do this with standard fonts in our PC software as well.

Are there any special characters what are commonly available in Arial, etc.?