Step 1: Divide the number into separate digits:
0346 => 0 3 4 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 3 = 3
3 to 4 = 1
4 to 6 = 2
6 to 0 = 6
Step 3: Combine the filters to a string:
3 1 2 6 = 3126