1
Input: 10 → [?] → 9, what is the rule? =
2
Input: 2 → [?] → 4, what is the rule? =
3
Input: 3 → [?] → 0, what is the rule? =
4
Input: 4 → [?] → 8, what is the rule? =
5
Input: 9 → [?] → 45, what is the rule? =
8
Input: 6 → [?] → 18, what is the rule? =