Step 1: Divide the number into separate digits:
18206 => 1 8 2 0 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 8 = 7
8 to 2 = 6
2 to 0 = 2
0 to 6 = 6
6 to 1 = 5
Step 3: Combine the filters to a string:
7 6 2 6 5 = 76265