President Barack Obama was officially sworn in for a second term on Sunday, taking the oath of office in a short ceremony in the Blue Room of the White House. Chief Justice John Roberts administered the Constitutionally-required oath. According to the White House, First Lady Michelle Obama, first daughters Sasha and Malia were in attendance.

"I did it," the president said to his daughters after taking the oath.

For Obama, it's actually the third time he's done it. In an infamous scene at President Obama's historic Jan. 20, 2009, inauguration, Roberts flubbed the oath, so Obama was forced to take a "do-over" oath with the chief justice the next day.

The oath of office is historically taken on Jan. 20, officially the first day of a presidential term. But since the 20th fell on a Sunday, the public ceremony was scheduled for the 21st.

So when President Obama publicly takes the oath from Roberts at Monday's inauguration in front of an estimated 800,000 people on the National Mall, it will be--technically speaking--his fourth.

As ABC News noted, President Franklin Roosevelt was also sworn in four times but, unlike Obama, he was elected four times.

This time around, Roberts and Obama are leaving nothing to chance. After the president won re-election on Nov. 6, "the two men exchanged a copy of an oath card, containing the precise wording, punctuation, and emphasis of the 35-word recitation," an inauguration official told Reuters.

Vice President Joe Biden was sworn for his second term early Sunday at his residence on the grounds of the Naval Observatory by justice Sonia Sotomayor, the first Hispanic to administer a presidential oath. According to the New York Times, Biden "used the same 19th-century family Bible he has used in every swearing-in ceremony since he entered the Senate in 1973."