Step 1: Divide the number into separate digits:
99783 => 9 9 7 8 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 9 = 0
9 to 7 = 2
7 to 8 = 1
8 to 3 = 5
3 to 9 = 6
Step 3: Combine the filters to a string:
0 2 1 5 6 = 02156