Three different positions of the same dice are shown (figures 1 to 3). Find the number on the face opposite to the face having '1" .

4

Short trick :

Step 1)     In a dice there are numbers 1, 2, 3, 4, 5, 6

Step 2)  According to question  4  is common in all the dices and it shares it's boundary with all 2, 3 , 5 ,6 except 1.

Step 3)  So, the number 1 is on the face opposite the face showing '4'.