Step 1: Divide the number into separate digits:
7425 => 7 4 2 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 4 = 3
4 to 2 = 2
2 to 5 = 3
5 to 7 = 2
Step 3: Combine the filters to a string:
3 2 3 2 = 3232