The most successful students use a solution book to verify their work, not to copy it.
If you’d like, I can:
In the Kumon method, the Solution Book is not just an answer key; it is a teaching tool. kumon+math+level+o+solution+book
Websites like eBay, Etsy, or Reddit often have listings for "Kumon Level O Answers." Be extremely cautious: The most successful students use a solution book