I seriously doubt the accuracy of that number.
Fat man was dropped purposely on the industrial area where there would be as few civilian casualties as possible. The plan was to take out Japans aircraft and ship building capability.
That’s why I asked. It’s always interesting to hear how if it’s the good guys doing the killing, civilian and non-cambatants casualties are acceptable...but if it’s the bad guys killing good civilians and non-combatants, it’s heinous.