Three different position P, Q and R of dice are shown in the figures given below. 

Which number lies at the bottom face in position P?

3

In dice Q and R start from common number in clockwise direction:

Q    6   4   3

      ⇓   ⇓   ⇓

R    6   2   5

Here, we can see :

4 is opposite to 2 and

3 is opposite to 5

In dice P, 5 is on the top and 3 is opposite to 5.

Therefore, in dice P 3 lies at the bottom face.