Conic, your favorite math themed fast food drive-in offers 20 flavors which can be added to your soda. You have enough money to buy a large soda with 4 added flavors. How many different soda concoctions can you order if:
You refuse to use any of the flavors more than once?
You refuse repeats but care about the order the flavors are added?
You allow yourself multiple shots of the same flavor?
You allow yourself multiple shots, and care about the order the flavors are added?