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When I did the number differences , I worked out that if the difference between 2 numbers next to each other was an odd number , it added up to an odd number. Eg: the difference between 5 and 6 is 1 and it adds up to 11.This means consecutive numbers can go next to each other.
I started by putting a number in a box, then another in the one next to it, making sure to not put together 2 evens or 2 odds (otherwise it would always equal an even number).Therefore if I put down an odd number I had to put even numbers surrounding it. The best way to work it out is by putting consecutive numbers next to each other.