Step 1: Divide the number into separate digits:
4140 => 4 1 4 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 1 = 3
1 to 4 = 3
4 to 0 = 4
0 to 4 = 4
Step 3: Combine the filters to a string:
3 3 4 4 = 3344