Step 1: Divide the number into separate digits:
0602 => 0 6 0 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 6 = 6
6 to 0 = 6
0 to 2 = 2
2 to 0 = 2
Step 3: Combine the filters to a string:
6 6 2 2 = 6622