These are combinations and permutations.
For 11P4, you multiply 11*10*9*8
You stop when there are 4 numbers. ex: 11P3 = 11*10*9, 11P2 = 11*10
For 10C6, you do same as permutations but then divide by 6!
---> (10*9*8*7*6*5)/(6*5*4*3*2*1)
You can simplify this by cancelling the 5,6,8
---> (10*9*7)/3