A half page in a public library book was torn out by us and is missing; can i return ti without mentioning it?
Does the library usually charge for something like this? Even if they do it would inly be a very nominal amount of money. Ask the librarian. It will also make a kiddush H-shem, that you are honest, (the librarian might just be shocked that someone is so honest to ask such a question.) If you do have to pay something, you should.