Step 1: Divide the number into separate digits:
57711 => 5 7 7 1 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 7 = 2
7 to 7 = 0
7 to 1 = 6
1 to 1 = 0
1 to 5 = 4
Step 3: Combine the filters to a string:
2 0 6 0 4 = 20604