Step 1: Divide the number into separate digits:
3019 => 3 0 1 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 0 = 3
0 to 1 = 1
1 to 9 = 8
9 to 3 = 6
Step 3: Combine the filters to a string:
3 1 8 6 = 3186