\begin{array}{l} n = \frac{10500 \frac{k g}{m^{3}}}{0, 108 \frac{k g}{m o l}} 6, 02 \cdot 10^{23} \frac{1}{m o l} \\ \approx 5, 9 \cdot 10^{28} \frac{1}{m^{3}} \end{array}

${\begin {array} {l}n = \frac {10500 \frac {kg} {m^3}} {0,108 \frac {kg} {mol}} \, 6,02 \cdot 10^{23} \frac {1} {mol} \\ \approx 5,9 \cdot 10^{28} \frac {1} {m^3} \end {array}}$