President Barack Obama made one factual error in his first speech in office when he said, immediately after being sworn in:
Forty-four Americans have now taken the presidential oath.
It is true that Obama is counted as the 44th president, but he’s only the 43rd person to take the oath. Grover Cleveland is counted as both the 22nd and the 24th president.
Cleveland took the oath the first time in 1885, served four years and then was defeated by Benjamin Harrison in 1888. Harrison took the oath as the 23rd president in 1889. But then Cleveland won again in 1892, and took the oath of office for a second time in 1893, becoming the 24th president as well as the 22nd.
So while we count Obama as the 44th president, he’s only the 43rd person who has been president. It’s just an odd quirk in the way historians chose to number presidents.