(And getting away from the purse.)
“The result was that in the Fat Man bomb, about 1 kilogram (2.2 lb) of the 6.2 kilograms (14 lb) of plutonium in the pit (about 17%) fissioned. In this process 1 gram (0.035 oz) of matter in the bomb was converted into the active energy of heat and radiation (see mass-energy equivalence for detail), releasing the energy equivalent of 21 kilotons of TNT or 88 terajoules.[citation needed]“
One gram of matter converted to energy equaled 21,000 tons of chemical explosive.
http://en.wikipedia.org/wiki/Fat_Man
By the way, the plutonium in that bomb came from a variety of sources, including captured German material.