If your grandmother insists she can't figure out Facebook, introduce her to Florence Detlor. At 101, she's the oldest registered user of the social networking site, Mashable reports. Facebook COO Sheryl Sandberg posted a picture of herself and Mark Zuckerberg with Detlor at the company's headquarters, which nearly 7,000 people have "liked" so far. Detlor's profile indicates she lives in the same city as Facebook HQ, Menlo Park, and that she's been a member of the site for three years. (More Florence Detlor stories.)