Chapter 2 - Atoms, Molecules, and Ions - Additional Exercises - Page 78: 2.87d

$1.7^{-11}$ C/wa

The charge of an electron in wa is $9.6*10^{-9}$ wa, and the charge of an electron in coulombs is $1.60218*10^{-19}$ C. Equating the two and dividing each side by $9.6*10^{-9}$ wa gives you $1.7^{-11}$ C/wa