Step 1: Divide the number into separate digits:
51161 => 5 1 1 6 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 1 = 4
1 to 1 = 0
1 to 6 = 5
6 to 1 = 5
1 to 5 = 4
Step 3: Combine the filters to a string:
4 0 5 5 4 = 40554