Hello. I have the following sticking point:

In the gym, I do various courses. There are quite many attractive girls there. The problem is that during the course it is impossible to talk to them, everybody works out. The only chance is to talk is before or after the course.

Usually, I approach to after the course with something based on the situation. In most cases, the girls respond positively. However, at this point, everybody is leaving and the girls are already on the way to the showers or home.

Due to the very short amount of time I am not sure how to go on. Asking for the number has not worked so well for me in cases of short conversations. What would you do, go direct ("I like you") and invite her to an instant date ("come and have a coke with me at the bar! ")? Or is there another way to get something out of this situations?