Step 1: Divide the number into separate digits:
03771 => 0 3 7 7 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 3 = 3
3 to 7 = 4
7 to 7 = 0
7 to 1 = 6
1 to 0 = 1
Step 3: Combine the filters to a string:
3 4 0 6 1 = 34061