A children’s story about a girl who goes off to sea with a bunch of toys, including a toy soldier (but he was probably a toy sailor or sea captain)? Eventually, a duck leads a mutiny of all of the toys with no teeth against the toys with teeth. I must have read this in the 70’s as a hardcover in my school library and it seemed turn-of-the-century but who knows. I believe it had a sad ending.
I think this is Amy’s Eyes, by Richard Kennedy. You can see the book cover and a summary here: https://en.wikipedia.org/wiki/Amy%27s_Eyes
How on Earth did you find that? I think it must be it– I do think the duck believed in numerology 🙂 It was one of those books that I took a while reading, but years later looked back on it and thought “what in the world was THAT?”