Step 1: Divide the number into separate digits:
1824 => 1 8 2 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 8 = 7
8 to 2 = 6
2 to 4 = 2
4 to 1 = 3
Step 3: Combine the filters to a string:
7 6 2 3 = 7623