Step 1: Divide the number into separate digits:
00720 => 0 0 7 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 7 = 7
7 to 2 = 5
2 to 0 = 2
0 to 0 = 0
Step 3: Combine the filters to a string:
0 7 5 2 0 = 07520