Step 1: Divide the number into separate digits:
1652 => 1 6 5 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 6 = 5
6 to 5 = 1
5 to 2 = 3
2 to 1 = 1
Step 3: Combine the filters to a string:
5 1 3 1 = 5131