Answer
$6.40*10^{-13}$ zirkombs.
Work Step by Step
We divide each of the charges by the smallest charge to find:
$$\frac{2.56*10^{-12}}{6.40*10^{-13}}=4$$
$$\frac{7.68*10^{-12}}{6.40*10^{-13}}=12$$
$$\frac{3.84*10^{-12}}{6.40*10^{-13}}=6$$
$$\frac{6.40*10^{-13}}{6.40*10^{-13}}=1$$
Because $6.40*10^{-13}$ produced the smallest integer value, the charge of electron is $6.40*10^{-13}$ zirkombs.
