Step 1: Divide the number into separate digits:
25941 => 2 5 9 4 1
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 4 = 5
4 to 1 = 3
1 to 2 = 1
Step 3: Combine the filters to a string:
3 4 5 3 1 = 34531