1348 and 3148
How many different positive numbers (integers) can you make using each of the digits 1, 2, 3, 4, once only, and a take away sign?
Example 31-24, or 413-2
There are four solutions.
Find a way to write the digits 1 through 9 in sequence, so that the numbers determined by any two consecutive digits are divisible either by 7 or by 13.