Step 1: Divide the number into separate digits:
5607 => 5 6 0 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 6 = 1
6 to 0 = 6
0 to 7 = 7
7 to 5 = 2
Step 3: Combine the filters to a string:
1 6 7 2 = 1672