Where is the number placed in each space?

At the point farthest from the space's lines, where there is the most room, and as big as the space allows: at least 7 pt (KDP's smallest text, and the first thing buyers complain about in other books is tiny numbers), and at most 22 pt for toddlers, 15 pt for kids, 14 pt for seniors, 11 pt for bold and easy, 8 pt for detailed. The numbers are dark grey in the book's font, so they disappear under the pencil but stay readable.