Step 1: Divide the number into separate digits:
15747 => 1 5 7 4 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 5 = 4
5 to 7 = 2
7 to 4 = 3
4 to 7 = 3
7 to 1 = 6
Step 3: Combine the filters to a string:
4 2 3 3 6 = 42336