Step 1: Divide the number into separate digits:
2592 => 2 5 9 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 5 = 3
5 to 9 = 4
9 to 2 = 7
2 to 2 = 0
Step 3: Combine the filters to a string:
3 4 7 0 = 3470