A person scuffing her feet on a wool rug on a dry day accumulates a net charge of -40.6 mC. How many excess electrons does this person get? By how much does her mass increase?
first I used # of electrons aquired= given charge/ charge on one electron

so # OF ELEC = 4.06*10^-6/ 1.6*10^-19= 2.5375*10^-25 but that wasn't right... so I don't know what to do...

A person scuffing her feet on a wool rug on a dry day accumulates a net charge of -40.6 mC. How many excess electrons does this person get? By how much does her mass increase?
first i used # of electrons aquired= given charge/ charge on one electron

so # OF ELEC = 4.06*10^-6/ 1.6*10^-19= 2.5375*10^-25 but that wasnt right... so i dont know what to do...

first, 40.6 mC is not 4.06*10^{-6}C

second, 10^{-6}/10^{-19} = 10^{13}, not 10^{-25}, so you've typed something into your calculator wrong.

Take these into mind and try again. I believe that your method is correct.