Step 1: Divide the number into separate digits:
00820 => 0 0 8 2 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 0 = 0
0 to 8 = 8
8 to 2 = 6
2 to 0 = 2
0 to 0 = 0
Step 3: Combine the filters to a string:
0 8 6 2 0 = 08620