Step 1: Divide the number into separate digits:
31404 => 3 1 4 0 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 1 = 2
1 to 4 = 3
4 to 0 = 4
0 to 4 = 4
4 to 3 = 1
Step 3: Combine the filters to a string:
2 3 4 4 1 = 23441