Permutation or Combination

[sickplaya]

In a 4 x 4 square checker board (total of 16 checker spaces), 3 random checkers are placed in different squares. How many combinations are possible?

My reasoning is that this should be 16C3 = 560 possibilities rather than 16P3 because the question is not asking for a specific order or placement of the checkers on the board. I'm not sure though.

 

[pka]

In a 4 x 4 square checker board (total of 16 checker spaces), 3 random checkers are placed in different squares. How many combinations are possible?
My reasoning is that this should be 16C3 = 560 possibilities

Your reasoning is correct.
I also think that is the intent of the problem.
However, that answer assumes that that 4-grid is oriented.
That is, a usual 4-grid can be rotated through 90, 180, 270 degrees to get the same 4-grid. Thus, your answer may need to be divided by four?