Step 1: Divide the number into separate digits:
0445 => 0 4 4 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 4 = 4
4 to 4 = 0
4 to 5 = 1
5 to 0 = 5
Step 3: Combine the filters to a string:
4 0 1 5 = 4015