Step 1: Divide the number into separate digits:
5031 => 5 0 3 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 0 = 5
0 to 3 = 3
3 to 1 = 2
1 to 5 = 4
Step 3: Combine the filters to a string:
5 3 2 4 = 5324