Three or four. It really depends on the quality of the Mountain. You see, another little known fact is that the value of a Mountain is dependent upon it's purity. Sadly, the only way to test it's purity is to bite off one of the corners!. Unfortunately, when you do that this lowers the value of the Mountain and turns it into what is called a Volcano, as one tip is missing. It can be quite damaging to one's teeth to bite off a mountain, but at least it has a good taste. It tastes like the candies called "Red Hots".
Most people just give it a value of three or four hills as hills are not worth very much. Most folks don't want to risk breaking their teeth you see. This is why there are more mountains than volcano's.