Step 1: Divide the number into separate digits:
02042 => 0 2 0 4 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 2 = 2
2 to 0 = 2
0 to 4 = 4
4 to 2 = 2
2 to 0 = 2
Step 3: Combine the filters to a string:
2 2 4 2 2 = 22422