"Climb", "go up", and "go down" sound natural, but "ascend" and "descend" sound extremely formal. "Sail down 5 flights of stairs" implies that you are going down really fast, and it sounds more informal. I can't think of any other ways of expressing this idea though. I always say "go up", "go down", or "climb".

Ok, speaking of what you normally do... For an example, the 3rd to the 8th floor. I climb 5 flights of stairs every day. (2nd most common) I ascend 5 flights of stairs each day. (very formal and not so common) I go up 5 flights of stairs each and every day. (most common and rather informal) You may also say... I flew up the stairs. I hurried up the stairs. I slowly/carefully climbed the stairs. For an example, the 8th floor to the 3rd floor. (everyday or normally) I sail down stairs quickly. (normally happens....common if you are saying you are in a hurry) I descend 5 flights of stairs each day. (very formal and not so common) I go down 5 flights of stairs every day. (common and informal) For a specific event: I jumped down the stairs. (jumped over many of the steps) I leaped down the stairs. (jumping over many of the steps) I stumbled down the stairs. (almost falling down) I bounced down the stairs. (if I fell down) I also appreciate it if you give me other expressions. Note: You would use the past tense of these when talking about specific times that you climbed or went down the stairs! (climbed, went down, descended, sailed) Hope this helps you a bit!?!

I searched about it on the internet and I found some sentences: Is it more efficient to climb stairs one at a time or two at a time? I can go up 3 steps at a time. I'm still learning, too. CMIIW