d
\({\text{n}} = \frac{t}{{{\tau _{\frac{1}{2}}}}} = \frac{{24}}{{24 \times 138.6}} = \frac{1}{{138.6}}\)

હવે \(\frac{{N}}{{N_0}} = (\frac{{1}}{{2}} )^n = (\frac{{1}}{{2}} )^{\frac{{1}}{{138.6}}} \)

\( \Rightarrow \,\,N = 10,00000{\left( {\frac{1}{2}} \right)^{1/138.6}}\) \( = 995011\)

\(\therefore\) વિભંજનની સંખ્યા \(= 1000000 - 995011 = 4989 \approx 5000\)