Want to nail a job interview? Need advice on hiring the right employee? Well, Mark Zuckerberg just shared some pretty simple advice.

Speaking to an audience recently at Mobile World Congress in Barcelona, the Facebook co-founder and CEO revealed the one question he looks to answer when considering a job applicant to work directly under him.

Would I like working for this person?

"I will only hire someone to work directly for me if I would work for that person," Zuckerberg said according to reports. "It's a pretty good test and I think this rule has served me well."

The 30-year-old multi-billionaire and head of the largest social media platform on the planet, used Facebook COO Sheryl Sandberg as an example of his rule, as he handpicked her for the position. Although she works for him, he says that he considers Sandberg a mentor adding that she’s someone who is a key part of making Facebook the business that it is.

He was quick to note, however, "Facebook is not a company for everyone in the world," as there is a lot required out of each individual employee.