A star initially has $10^{40}$ deuterons. It produces energy via the
processes $_1H^2+_1H^2 \rightarrow _1H^3+p$ and $_1H^2+_1H^3 \rightarrow _2{He}^3+n$.
If the average power radiated by the star is $10^{16}$ W, the
deuteron supply of the star is exhausted in a time o f the order of
$M(H)^2=2.014 \, amu;$ $M(n)=1.008 \, amu;$
$M(p)=1.007 \, amu;$ $M(He)^2=4.001 \, amu;$