The first dropping of the Atomic bomb on Hiroshima killed 90,000 to 146,000 people. Half of the people died on the first day of the Hiroshima bomb and over the next 2 to 4 months the other half of the people died.
The second dropping of the bomb on Nagasaki killed 39,000 to 80,000 people. The deaths happened the same way it did for Hiroshima.
