Four times? For a president who is only entering his second term? It's complicated.
Recall that in 2009, the president and the chief justice got off to a rocky start. They had to do it twice.
Article II, Section 1 of the Constitution determined the wording of the oath: "I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States."
But in 2009 when Roberts began, without notes, he stumbled on the words, which caused the President to stumble. They got through it, but a couple of words were rearranged and omitted. So the next day, the White House asked if Roberts could come by and redo the oath, out of an abundance of caution, so that no one could ever question the President's legitimacy.
Flash forward to 2013.
The Constitution says: "The terms of the President and Vice President shall end at noon on the 20th day of January." This year the 20th falls on a Sunday.
Historically, inaugural ceremonies are not held on Sunday because courts and other public institutions are not open.
So the president and the chief justice will meet at the White House in the Blue Room at 11:55 a.m. on Sunday for the official swearing-in. It will be covered by the White House pooled press.
And because this is the last inauguration for the President, presumably that will be the last presidential oath. If all goes according to plan.