They can count? lol! well I thought about that I just don't know that they're all going to hatch on the same day... long story short one hen went broody on top 6 eggs, I gave her an extra 5 at night but once she went broody her daughter decided to go broody too, but she wasn't done laying.. so she laid an extra 2 eggs (as of yesterday after I numbered them). They mom went broody last Friday and the last egg was laid sun or mon. I've heard they'll stay on the eggs until they've all hatched but that wouldn't allow her to properly care for the ones that have hatched. However, I do believe either way it will work out since there are 2 hens sharing 13 eggs... so what's another 10 more ... that may be a little much for them... don't you think???