To sum up: Abe had more schooling
Two maths notebook pages belonging to Abraham Lincoln suggest the 16th US president, who was known to downplay his formal education, may have spent more time in school than usually thought.
And the Illinois State University maths professors behind the discovery say the work shows Lincoln was no slouch either. Profs Nerida Ellerton and Ken Clements at the university in Normal said they recently confirmed that the two pages were part of a previously known maths notebook from Lincoln's childhood. It was found in the archives of Houghton Library at Harvard University, where it remains.
The book, known as a cyphering book in Lincoln's day, is a sort of maths workbook in which Lincoln wrote problems and their answers. It is the oldest known Lincoln manuscript.
Based on the difficulty of the problems involved and dates on some of the pages - 1824 and, on the recently authenticated pages, 1826, when Lincoln was 17 - Lincoln probably worked in the book intermittently over several years while his family lived in Indiana, the married professors said.
They think he could have started as early as 10 and believe his work happened while he was in school. "Most people say he went to school for anything between three months and nine months" over the course of his life, Prof Clements said. "We think he went to school (up to) two years."
And very little of the work is wrong, he added. "He made very few errors and he always knew what he was trying to do," Prof Clements said. "We've studied thousands of these cyphering books. You don't always get the feeling that 'this guy knew what he was doing'."
The professors' find suggests Lincoln may have gone to school over as many as three to five winters, according to historian Daniel Stowell, director of the Papers of Abraham Lincoln project at the Abraham Lincoln Presidential Library in Springfield. The library owns one previously identified page of the book. "They are arguing with some merit that a cyphering book would have been created in a school setting," Mr Stowell said. "It does at least open the possibility that he may have had more formal schooling than originally thought. Not a whole lot more, but still more."
The pages - attached as a single leaf - include word problems that are the equivalent of roughly eighth-grade modern work, Prof Clements said. Lincoln is known to have later studied trigonometry and geometry on his own.
The newly-authenticated pages have been in the Harvard library's archives since 1954. They were known as Lincoln documents, but their origin was not known, the professors said. The two looked at the documents as they researched a book they have written on maths books from the period.
A letter from former Lincoln law partner William Herndon from 1875 that accompanied the papers, describing them, made the authentication relatively straightforward, Prof Clements said. Lincoln's stepmother, Sarah Bush Lincoln, gave the cyphering book to Mr Herndon after Lincoln's death, and Mr Herndon then gave them to other people, Mr Stowell said.