Step 1: Divide the number into separate digits:
1292 => 1 2 9 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 2 = 1
2 to 9 = 7
9 to 2 = 7
2 to 1 = 1
Step 3: Combine the filters to a string:
1 7 7 1 = 1771