Google does.
Well they are both wrong........since I don't expect this to be a multi-page thread, I'll supply you with the very strange answer........
On Saturday, March 3, 1849, by law, the presidential term of James A. Polk officially ended, he vacated the presidential residence, as did all of his staff and aids.........His cabinet also resigned as well, as was the custom of that time.
The then President-elect Zachary Taylor, and his Vice President-elect Millard Fillmore, both G*d-fearing Christian men, refused to be inaugurated on the following day, which was the Sabbath......no one gave a great deal of thought to it until about three AM on Sunday, March 4, 1849, when Federal Circuit Judge Willie Magnum discovered that it was a violation of the Constitution for there not to be a sitting president.
Considering the circumstances, and the fact that both the President-elect, and the VP-elect refused yet again to be sworn in until Monday, Judge Magnum consulted his staff, and at three AM on that Sunday morning awoke Senator David Rice Atchison, from Plattsburg, Missouri, who was, at that time the President of the Senate.......
Judge Magnum advised Senator Atchison that since he was the next in the Constitutional line of succession, that he must be sworn in as President of the US, until Zachary Taylor was inaugurated on the following day.
Standing in his bedchamber, in his nightshirt and cap, Senator Atchison placed his hand on the Bible, and took the presidential oath of office administered by Judge Magnum, in the presence of four witnesses, after which, he returned to bed, and slept through much of the following day.
David R. Atchison, therefore, for a period of one day, was the twelfth President of the United States, and his gravemarker in his home town of Plattsburg, MO, bears the inscription:
"President of the United States for One Day"doc