Riddle: There are two species of citizens on a foreign planet: Hamburgs and Helphands. There are 10,000 Hamburgs, and Helphands make up 50% of the population. How many Helphands are on the foreign planet?
Answer: There are 10,000 Helphands on the foreign planet. If there are only two species of citizens on the planet, and Helphands make up 50% of the population, then Hamburgs must make up the other 50% of the population, with 10,000 of them. If there are 10,000 Hamburgs, then there are also 10,000 Helphands.
Source: https://riddles.com/11413