Step 1: Divide the number into separate digits:
84051 => 8 4 0 5 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 4 = 4
4 to 0 = 4
0 to 5 = 5
5 to 1 = 4
1 to 8 = 7
Step 3: Combine the filters to a string:
4 4 5 4 7 = 44547