Step 1: Divide the number into separate digits:
20650 => 2 0 6 5 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 0 = 2
0 to 6 = 6
6 to 5 = 1
5 to 0 = 5
0 to 2 = 2
Step 3: Combine the filters to a string:
2 6 1 5 2 = 26152