Step 1: Divide the number into separate digits:
50902 => 5 0 9 0 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 0 = 5
0 to 9 = 9
9 to 0 = 9
0 to 2 = 2
2 to 5 = 3
Step 3: Combine the filters to a string:
5 9 9 2 3 = 59923