Step 1: Divide the number into separate digits:
59661 => 5 9 6 6 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 9 = 4
9 to 6 = 3
6 to 6 = 0
6 to 1 = 5
1 to 5 = 4
Step 3: Combine the filters to a string:
4 3 0 5 4 = 43054