Old Farmer Palmer has a herd of cows, but he always seems to forget how many animals there are. When he counts them he just makes sure he can see 6 cows from each window of his house.
One night, however, Russell the Rustler took away half of the herd. Farmer Palmer didn’t notice for ages because the next morning he could still see 6 cows from each window. How was it done?
There are many possible solutions once you get the idea. Below is one possible solution.