Step 1: Divide the number into separate digits:
7926 => 7 9 2 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 9 = 2
9 to 2 = 7
2 to 6 = 4
6 to 7 = 1
Step 3: Combine the filters to a string:
2 7 4 1 = 2741