How old was Samuel Clemens (Mark Twain) when he left school?

Samuel Langhorne Clemens, better known by his pen name, Mark Twain, was born on November 30, 1835. In the tiny village of Florida, Missouri the sixth child of John and Jane Clemens. When he was 4 years old, his family moved to nearby Hannibal, a bustling town of 1,000 people.

Sam Clemen's kept up his schooling until he was 12 years old, when—with his father dead and the family needing a source of income—he found employment as an apprentice printer at the Hannibal Courier, which paid him with a meager ration of food. In 1851, at 15, he got a job as a printer and occasional writer and editor at the Hannibal Western Union, a little newspaper owned by his brother, Orion.

Some of his best known works include "Roughing It", " The Gilded Age", "The Adventures of Huckleberry Finn" and "The Adventures of Tom Sawyer".