The Americans retaliated against Japan for attacking Pearl Harbor by using Little Boy the atomic bomb on Hiroshima, Japan. The Little Boy killed 146,000 people. Three days later America dropped another bomb called Fat Man, which was substantially bigger than the first one. Even though the Fat Man was bigger it killed 80,000, a little more than half of the amount of the first bomb. The Fat Man weighed 5.15 tons which is as much as an elephant. The Little Boy was 9,700 pounds which is the same weight as 6 cows put together.