check my work please, Find percent ionization of ammonia?

Question

Check my work and sig figs, and tell me if I got this right, thanks!

Calculate the percent ionization of ammonia in a 0.050 M NH3 solution.

okay I got the pKb off a website, it was 4.76, I convert this to Kb by 10^-4.76= 1.7x10^-5

okay, I use the ICE method and come up with x^2/0.050M-x=1.7x10^-5

I solve this for x and get x= 9.13x10^-4 this is my concentration of [OH-]

so % ionization= 9.13x10^-4/0.050= .0183 x 100 = 1.83%

Hows this look?

Answer 1

Would only be 1.8% since you only have two significant figures in your concentration. Otherwise, it looks OK.

Answer 2

Absolutely right. I found 1.86% degree of ionization.