Can Facebook users check if their accounts have been hacked by commenting "@[4.0]" on posts?

  • Published 8 September 2015

In September 2015, a rumor started circulating via Facebook that users of the social network could check to see if their accounts had been hacked by commenting “@[4:0]” on photographs. If the code turned into the name “Mark Zuckerberg” when posted, that supposedly meant the posting account had not been compromised:

While typing @[4:0] on Facebook will often result in Mark Zuckerberg’s name appearing (results vary depending on operating system), this is not the result of a Facebook security check. This trick has more to do with code, Facebook’s mention system, and Mark Zuckerberg’s site ID than it does with hacking.

In 2011, after a similar trick (explaining how a long string of numbers followed by the @ symbol could turn into the words “I’m Gay”) went viral, Today.com reporter Rosa Golijan explained that the numbers following the “at” (@) symbol simply corresponded to the ID number of a particular Facebook user or Facebook page:

The “@” symbol and surrounding brackets instruct Facebook to convert the ID number into the page’s title in a comment or Wall post.

In this case, since Facebook founder and CEO Mark Zuckerberg’s Facebook ID number is 4, the “4:0” corresponds to his account and is replaced with his name when inserted into a Facebook post.

Since 1994
A Word to Our Loyal Readers

Support Snopes and make a difference for readers everywhere.

  • David Mikkelson
  • Doreen Marchionni
  • David Emery
  • Bond Huberman
  • Jordan Liles
  • Alex Kasprak
  • Dan Evon
  • Dan MacGuill
  • Bethania Palma
  • Liz Donaldson
  • Vinny Green
  • Ryan Miller
  • Chris Reilly
  • Chad Ort
  • Elyssa Young

Most Snopes assignments begin when readers ask us, “Is this true?” Those tips launch our fact-checkers on sprints across a vast range of political, scientific, legal, historical, and visual information. We investigate as thoroughly and quickly as possible and relay what we learn. Then another question arrives, and the race starts again.

We do this work every day at no cost to you, but it is far from free to produce, and we cannot afford to slow down. To ensure Snopes endures — and grows to serve more readers — we need a different kind of tip: We need your financial support.

Support Snopes so we continue to pursue the facts — for you and anyone searching for answers.

Team Snopes