Step 1: Divide the number into separate digits:
69218 => 6 9 2 1 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 9 = 3
9 to 2 = 7
2 to 1 = 1
1 to 8 = 7
8 to 6 = 2
Step 3: Combine the filters to a string:
3 7 1 7 2 = 37172