Step 1: Divide the number into separate digits:
76420 => 7 6 4 2 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 6 = 1
6 to 4 = 2
4 to 2 = 2
2 to 0 = 2
0 to 7 = 7
Step 3: Combine the filters to a string:
1 2 2 2 7 = 12227