Question

Two positions of a cube are as follows.

Point out which number will be on the top if number 3 is at the bottom.

Answer 1

The cube in this question is citing to a cubic dice which has six faces
Each side is denoted by dots ranging from 1 to 6. 
Most of the dices have got dots behind them while some have got numbers.
However, both use the same conventional method for marking the sides.
Generally,
1 is opposite to 6
2 is opposite to 5 and 
3 is opposite to 4

Therefore when 3 is at the bottom, 4 will be at the top
This information gives us the answer which is 4