According to Brookings, based on 1996 dollars, the average cost for the atomic bombs (Gadget, Little Boy, Fat Man and one unused) were $5 billion a piece. Estimates related to developing the atomic bomb in the USA employed around 100k people. Russia employed approximately 500k people. Costs are ignored when a dire need to find a solution to end WWII and implications of Hitler developing one hastened America’s atomic bomb program.