Fermi estimate: the energy in a gram of antimatter

speedOfLight = 299792458;
antimatterGrams = 1;
annihilationJoules = 2 (antimatterGrams 10^-3) speedOfLight^2

22468879468420441/125

N[annihilationJoules]

1.7975103574736353*^14

hiroshimaBombs = N[annihilationJoules/(6.3 10^13)]

2.8531910436089447

tonsOfTnt = N[annihilationJoules/(4.184 10^9)]

42961.52862030677

usHouseholdYears = N[annihilationJoules/(10800 3.6 10^6)]

4623.22622807005