How to show asterisk in the "fill in the blank" question?

For "fill in the blank" question, if I want to ask a question like:

45 * 2 = <blank>

Then I need to type 45 * 2 = *90*

However, the multiplication sign * has a different meaning here so it doesn't work. Is there a way to get around it (like the escape character)?

Also, I have to use the asterisk as the multiplication sign, and cannot replace it with x or X.

Thank you!