Here's a good one: Rambo and Shyambo are farmers who own a bunch of cows together. One day they decide to sell their cows and buy goats instead. They sell all their cows - each cow gets sold for an amount that is equal to the total number of cows they had, i.e. price of a cow = number of cows they owned. From the money they get, they buy goats - each goat costs 10 dollars. They have some money left over, not enough to buy another goat, so they buy one chicken with the rest of that money. One day, they get into a fight and decide to split up. They divide the goats among themselves and find out that there is one goat left. Rambo says to Shyambo - I'll take the last goat, you can have the chicken. Shyambo says - No way! A chicken costs less than a goat! Rambo says - I'll also give you one of my dogs and we will be even. Shyambo agrees. How much does a dog cost?