Step 1: Divide the number into separate digits:
9760 => 9 7 6 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 7 = 2
7 to 6 = 1
6 to 0 = 6
0 to 9 = 9
Step 3: Combine the filters to a string:
2 1 6 9 = 2169