Answer:
1?3
256
Explanation:
If one is close to 2, then but so is five, and 6 is near five then they all have to be on there own row. Seeing as 3 is close not close to 1, or 2, it has to be the furthest away from them as it can be, and the questionmark is there because you only have five numbers, (1,2,3,5,6) so there isn't enough info for the question mark to have an answer.
