[yefragetuwrabrumuy]

A Hiroshima/Nagasaki type atomic bomb is about 25-30 Kt (kilotons of TNT). So 25 x 40 = 1000 Kt, to a maximum of 1200 Kt.

[Paal Gulli]

"A Hiroshima/Nagasaki type atomic bomb is about 25-30 Kt....

Nope.

Little Boy ... exploded with an energy of approximately 15 kilotons of TNT

https://en.wikipedia.org/wiki/Little_Boy

"Fat Man" (also known as Mark III) ... released the energy equivalent to the detonation of 21 kilotons of TNT

https://en.wikipedia.org/wiki/Fat_Man

[Az Joe]

No, Hiroshima was 15-20k at most, Nagasaki the same