Step 1: Divide the number into separate digits:
7527 => 7 5 2 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 5 = 2
5 to 2 = 3
2 to 7 = 5
7 to 7 = 0
Step 3: Combine the filters to a string:
2 3 5 0 = 2350