Step 1: Divide the number into separate digits:
7024 => 7 0 2 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 0 = 7
0 to 2 = 2
2 to 4 = 2
4 to 7 = 3
Step 3: Combine the filters to a string:
7 2 2 3 = 7223