In 1st and 2nd Dice, 6 is a common number. So, starting clockwise from 6. 1 is the opposite face of 4 and 2 is the opposite face of 5. In 1st and 3rd Dice, 4 is a common number. So starting clockwise from 4. 3 is the opposite face of 6 and 2 is the opposite face of 5. Hence, the correct answer is "3".