In LBT 5, Petrie's mom counts her children before finding out Petrie is missing, though she might have going by names. In LBT 2, Ducky figures out that all of the eggs are safely in the nest, though she mght have just realized that there aren't any spaces or gaps. In "Canyon of Shiny Stones," had the contest not been so one-sided, they must have known how to distinguish who found the most geodes.