As many as you like. ;) It's not about how many stairs you run up and down, but about how long you work out, and at what heart rate. I would aim more for time; if you want to do the steps (be careful!) then aim for at least 10 minutes.
I have NO idea how you'd track that, though.
Writer, mother, wife, and breadwinner. I love to run, but running doesn't love me, so I'm switching to my low-impact bike.
I'm not pregnant, just fat: My blog. fatnotpregnant.blogspot.com/
| current weight: 190.6