Physics
posted by rick .
How many electrons must be removed from an electrically neutral silver dollar to give it a charge of +2.8 µC?

Do you know the charge per electron?
number*charge per electron= total charge
solve for number. 
i don't know what you mean about the charge of the electron? or what number do you times it by.

http://scienceworld.wolfram.com/physics/ElectronCharge.html
number electrons= totalcharge/chargeperelectron 
q=(n*e).....(i)
where, q= charge,
n=number,
e= charge of an electron
n=q/e....(i) (from equation i)
given,q= +2.8mc= +2.8*10^6 c
we know, charge of an electron(e)=1.6*10^19 c
hence n= (2.8*10^6)/(1.6*10^19)
= 1.75*10^13
so, 1.75*10^13number of charges should ne removed. 
q=(n*e).....(i)
where, q= charge,
n=number,
e= charge of an electron
n=q/e....(i) (from equation i)
given,q= +2.8mc= +2.8*10^6 c
we know, charge of an electron(e)=1.6*10^19 c
hence n= (2.8*10^6)/(1.6*10^19)
= 1.75*10^13
so, 1.75*10^13number of charges should be removed. 
what? i don't get it. ISn't 1.72*10^3 the number of electrons for 2.7uC?

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1.5x10^13