A single electron has a charge of
[tex]e=-1.6 \cdot 10^{19}C[/tex]
Therefore, if we have an excess of [tex]N=6.0\cdot10^6[/tex] electrons, the total net charge will be the product between the charge of a single electron and the total number of electrons in excess:
[tex]Q=Ne=(6.0\cdot10^6)(-1.6 \cdot 10^{-19}C)=9.6 \cdot 10^{-13}C[/tex]
