It depends on the person, how fast they are running, the grade of the incline, how long they have been running..... a little too much to be considered to just give a flat out answer, even an estimate.

If you really want to figure out an average for yourself, you can run on a treadmill with a computer which will tell you approximately how many calories you've burned while using it.

It depends on:
1. what percentage of your maximum heartrate you reach
2. how heavy you are
3. how long you run
4. heat (sunny day vs normal day)
5. wind resistance (running against wind is obviously harder)
6. and probably lots of other intangible factors.