I thought you agreed that it was one bomb though...
What I have said all along is that the Nagasaki and Hiroshima bombings were conducted with just one bomb each. No disagreement there.
Most aerial bombing missions during WWII in both the Pacific and European theatres were comprised of several planes each carrying mutiple bombs. SEVERSKY CONCLUDED THAT THE LARGE SOLITARY BOMB DROPPED ON HIROSHIMA WAS NOT MORE POWERFUL THAN THE COLLECTIVE DESTRUCTIVE POWER OF ONE OF THESE BOMBING MISSIONS. To my memory, he used the figure of 200-tons of TNT, but I do not have the essay in front of me right now. He also compared it with one of the large blockbuster bombs used in New York to destroy a large condemned building.
Quite revealingly, one of Seversky's critics, a US Army general, in the May 1946 reply to Seversky's February article argued against Seversky asserting that an atom bomb dropped from overhead would almost assuredly destroy the better half of the Empire State Building leaving only some of the bottom floors. This is the armchair critic's limp wristed refutation? How amusingly pathetic.
Even from Seversky's contemporary critic one can discern the accuracy of his comparison of the Hiroshima and Nagasaki "atom" bombs with a demolition crew's large TNT blockbuster bombs.