The hiring process is pretty much standard. I submitted my application on the Google website, and in two weeks, a Google recruiter got in touch with me to schedule the phone interview. Basically, we went through my resume, discussing my past experience.

The interviewer asked me to write the code to implement the sqrt function, specifically double sqrt(double x).

There are quite a few answers if you Google it, but the most difficult part is explaining how you can test the code you just wrote.

I didn't do quite well, as software testing is not my traditional area of expertise. What I could think of off the top of my head was just to check some boundary conditions, which obviously wasn't what the interviewer expected.