Step 1: Divide the number into separate digits:
5702 => 5 7 0 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 7 = 2
7 to 0 = 7
0 to 2 = 2
2 to 5 = 3
Step 3: Combine the filters to a string:
2 7 2 3 = 2723