Step 1: Divide the number into separate digits:
59971 => 5 9 9 7 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 9 = 4
9 to 9 = 0
9 to 7 = 2
7 to 1 = 6
1 to 5 = 4
Step 3: Combine the filters to a string:
4 0 2 6 4 = 40264