Step 1: Divide the number into separate digits:
57790 => 5 7 7 9 0
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 9 = 2
9 to 0 = 9
0 to 5 = 5
Step 3: Combine the filters to a string:
2 0 2 9 5 = 20295