You are assembling a loft. One piece of wood has 8 screw holes in a straight row,

Question:

You are assembling a loft. One piece of wood has 8 screw holes in a straight row, but you can only find 6 screws (which look identical). In a hurry, you put the 6 screws in the 8 holes. How many outcomes are in the sample space, if exactly 6 holes are selected (and the order of selection does not matter)?