Calculating Electrostatic Force and Charge Imbalance in Tiny Water Drops

[Forceflow]

Two tiny, spherical water drops, with identical charges of -1.04 10-16 C, have a center-to-center separation of 1.5 cm.
(a) What is the magnitude of the electrostatic force acting between them?
(b) How many excess electrons are on each drop, giving it its charge imbalance?

Ok so, i know that the answer for A is 4.32159e-19.
However, I'm not sure how to do B.
I think its something like the total charge divided by a single charge. I'm not sure though.

 

[Kurdt]

for b you are correct. All you do is divide the charge on the drop by the charge on an electron.

 

[Forceflow]

650.

Thanks you.