Why my answers don't match the answer key a)=3.99*10^-6m/s, b)=1680m/s. I show how I solve each question below. Please explain.

A uniform electric field of 740 N/C is produced within a particle accelerator. Starting from rest, what are the following?
(a) the speed of an electron placed in this field after 23.8 ns have elapsed
V=Vo+at-->V=0+at-->V=at
t=(23.8ns)/10^-9=2.38*10^10s
F=(740N/C)(1C/1.6*10^-19e=4.625*10^21Ne
a=(4.625*10^21Ne)/(9.1094*10^-31ekg)=5.08*10^51m/s^2
V=(5.08*10^51m/s^2)*(2.38*10^10s)=5.081.21*10^32m/s

(b) the speed of a proton placed in this field after 25.4 ns have elapsed
V=Vo+at-->V=0+at-->V=at
t=(25.4ns)/10^-9=2.54*10^10s
F=(740N/C)(1C/1.6*10^-19p=4.625*10^21Np
a=(4.625*10^21Np)/(1.67*10^-27pkg)=2.77*10^48m/s^2
V=(2.77*10^48m/s^2)*(2.54*10^10s)=7.03*10^58m/s

t=(23.8ns)/10^-9=2.38*10^10s You have to be kidding.