Step 1: Divide the number into separate digits:
9242 => 9 2 4 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 2 = 7
2 to 4 = 2
4 to 2 = 2
2 to 9 = 7
Step 3: Combine the filters to a string:
7 2 2 7 = 7227