Step 1: Divide the number into separate digits:
24490 => 2 4 4 9 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 4 = 2
4 to 4 = 0
4 to 9 = 5
9 to 0 = 9
0 to 2 = 2
Step 3: Combine the filters to a string:
2 0 5 9 2 = 20592