In 1790, in Alexandria, Virginia, an 80-year-old enslaved man astonished prominent visitors with feats of mental calculation so advanced they questioned whether he might once have rivaled Isaac Newton. His name was Thomas Fuller.
Though he never learned to read or write, his answers to complex arithmetic questions were immediate, precise, and verifiable—delivered without paper, pen, or formal education.
From West Africa to Virginia
Born around 1710 in West Africa, likely in the region between present-day Liberia and Benin, Fuller was abducted at the age of 14 and transported to Virginia in 1724. Enslaved by Elizabeth Cox of Alexandria, he lived and worked on a farm for decades.
Despite being illiterate, Fuller developed remarkable computational skills. His methods were never documented, but scholars like ethnomathematician Ron Eglash suggest his abilities may have roots in African oral traditions, particularly those of the Bassari people, who used trained specialists for mental arithmetic.
A Visit from the Pennsylvania Abolition Society
When Fuller was about 70, two members of the Pennsylvania Abolition Society, William Hartshorne and Samuel Coates, visited him after hearing of his abilities. Their visit was documented by Benjamin Rush, a Founding Father and physician. In a widely circulated article, Rush described three tests they gave Fuller.
First, he was asked how many seconds are in a year and a half. Fuller replied, after about two minutes: 47,304,000. Next, they asked how many seconds a man has lived if 70 years, 17 days, and 12 hours old. Fuller answered: 2,210,500,800. When corrected, he replied, “top, massa, you forget de leap year”—and when leap years were added, the total matched his answer. A final question, involving exponential multiplication of pigs over eight years, took him ten minutes. His answer: 34,588,806.
A Remark That Echoed
Though Fuller showed signs of aging—white hair and frailty—his mind remained sharp. When one visitor remarked it was a pity Fuller had no formal education, he reportedly replied, “No, Massa, it is best I had no learning, for many learned men be great fools.”
His abilities were later mentioned in abolitionist writings in France and England, including by Brissot and Grégoire, as evidence in arguments for equal rights.
A Story That Crossed the Atlantic
Fuller died in December 1790. His obituary noted that he could answer complex problems faster than people working them out by hand.
His story was later cited by the London-based Society for Effecting the Abolition of the Slave Trade as proof of intellectual capacity among the enslaved. His calculations, once tested and recorded, traveled farther than he ever could.
In 1790 Virginia, an 80-year-old enslaved man named Thomas Fuller stunned visitors with his mind.
Unable to read or write, he solved complex arithmetic problems faster than trained men using pen and paper.
His answers spread across America and Europe…🧵👇 pic.twitter.com/sbmpXOYqHt
— Detective Tiger's Stories (@TigerDetective) July 2, 2025