Three different positions of the same dice are shown. Find the number on the face opposite the face showing '2'.

5 4 3 1

1

Short trick : Step 1)     In a dice there are numbers 1, 2, 3, 4, 5, 6 Step 2)  According to question  2  is common in all the dices and it shares it's boundary with all 3, 4, 5 ,6 except 1. Step 3)  So, the number 1 is on the face opposite the face showing '2'.