Step 1: Divide the number into separate digits:
97972 => 9 7 9 7 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 7 = 2
7 to 9 = 2
9 to 7 = 2
7 to 2 = 5
2 to 9 = 7
Step 3: Combine the filters to a string:
2 2 2 5 7 = 22257