Don't ask her for her number. Ask her out on a date, then ask for her number so you can coordinate. Counter-intuitively enough, the more you ask of her, the more she thinks you deserve, and the likelier you get a yes. You don't want to take her number now and text for too long before going out on a date. You're at a place where you are attracted to each other and have an aura of mystery. The sooner you go out on a date, the more exciting it'll be. If you want any advice, hit me up. Stuttering has held me back in many areas, but I have always been successful with women.