Much of what is known about Fuller’s life comes from two sources: 1) a report on his mathematical abilities prepared by Dr. Benjamin Rush and published in the American Museum, or Universal Magazine in 1788; and 2) his obituary, which appeared in the Boston newspaper Columbian Centinel, on December 29, 1790. The latter lists his age at the time of his death as eighty, making his birth year about 1710. Describing Fuller as “very black,” the paper reported that he “was brought to this country at the age of fourteen and was sold as a slave with many of his unfortunate countrymen.” Rush noted that Fuller was a native of Africa and that “he had worked hard upon a farm during the whole of his life.”
At some point Fuller was purchased by Presley and Elizabeth Cox, who farmed 232 acres of land four miles west of Alexandria. He remained there the rest of his life, never learning to read or write and receiving no instruction in arithmetic. According to Rush, Fuller told two men who came to interview him late in his life that he taught himself “by counting ten, and that when he was able to count an hundred, he thought himself (to use his own words) ‘a very clever fellow.'” He then counted “the number of hairs in a cow’s tail, which he found to be 2872.” Fuller also told the men that he was grateful to Elizabeth Cox, whose husband had died in 1782, for not selling him, “which she had been tempted to do by offers of large sums of money, from several curious persons.”
Rush reports at length on the particulars of Fuller’s calculations. Two white men, both Quakers from Pennsylvania, traveled to the Cox farm and posed several problems for him to solve, including how many seconds are in a year and half (47,304,000) and how many seconds are in seventy years, seventeen days, and twelve hours (2,210,500,800). One of the men argued that the second solution was too large, but Fuller reminded him of leap years. A third question involved the increase of farm animals, and all questions were solved correctly, within a minute or two, and without the aid of paper or pencil. On another occasion Fuller performed calculations for two different men, one of whom called it a “pity” that he had not been better educated. Fuller replied that “many learned men be great fools.” The scholar William F. Mugleston has acknowledged the possibility that Fuller had savant syndrome, but he also argues that no evidence beyond Fuller’s specific arithmetic skills supports this. John Fauvel and Paulus Gerdes argue further argue that the evidence doesn’t support the idea that Fuller had a low IQ, and they point to “a rich tradition of mental calculations among illiterate people” in Africa.
Fuller died in 1790, and his story was often related in the context of antislavery literature, which sought to demonstrate the mental fitness of African Americans. In New Travels in the United States of America, published in English in 1792, the Frenchman J. P. Brissot de Warville paired Fuller’s story with that of James Derham, an enslaved man who learned to practice medicine in New Orleans. “These instances prove, without doubt,” Brissot de Warville wrote, “that the capacity of the negroes may be extended to any thing; that they have only need of instruction and liberty.”