# How many electrons would have to be removed from a coin to leave it with a charge of +1.6 xx 10^-7 C?

We assume that the coin has a net charge of zero. Recall that electrons have a negative charge, and specifically, they have a charge of $- 1.602 \times {10}^{- 19} \text{C}$ (coulombs).
+1.6xx10^(-7) cancel"C" xx "1 electron"/(-(-1.6xx10^(-19) cancel"C"))
$= \textcolor{b l u e}{{10}^{12} \text{electrons}}$