Step 1: Divide the number into separate digits:
6192 => 6 1 9 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 1 = 5
1 to 9 = 8
9 to 2 = 7
2 to 6 = 4
Step 3: Combine the filters to a string:
5 8 7 4 = 5874