Step 1: Divide the number into separate digits:
37212 => 3 7 2 1 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 7 = 4
7 to 2 = 5
2 to 1 = 1
1 to 2 = 1
2 to 3 = 1
Step 3: Combine the filters to a string:
4 5 1 1 1 = 45111