Step 1: Divide the number into separate digits:
4974 => 4 9 7 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 9 = 5
9 to 7 = 2
7 to 4 = 3
4 to 4 = 0
Step 3: Combine the filters to a string:
5 2 3 0 = 5230