Step 1: Divide the number into separate digits:
7299 => 7 2 9 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 2 = 5
2 to 9 = 7
9 to 9 = 0
9 to 7 = 2
Step 3: Combine the filters to a string:
5 7 0 2 = 5702