Thomas Fuller was an African, shipped to America as a slave in 1724. He had remarkable powers of calculation, and late in his life was discovered by antislavery campaigners who used him as a demonstration that blacks are not mentally inferior to whites.

Thomas Fuller, known as the Virginia Calculator, was stolen from his native Africa at the age of fourteen and sold to a planter. When he was about seventy years old, two gentlemen, natives of Pennsylvania, viz., William Hartshorne and Samuel Coates, men of probity and respectable characters, having heard, in travelling through the neighbourhood in which the slave lived, of his extraordinary powers in arithmetic, sent for him and had their curiosity sufficiently gratified by the answers which he gave to the following questions: First, Upon being asked how many seconds there were in a year and a half, he answered in about two minutes, 47 304 000. Second: On being asked how many seconds a man has lived who is 70 years, 17 days and 12 hours old, he answered in a minute and a half 2 210 500 800. One of the gentlemen who employed himself with his pen in making these calculations told him he was wrong, and the sum was not so great as he had said - upon which the old man hastily replied: stop, master, you forget the leap year. On adding the amount of the seconds of the leap years the amount of the whole in both their sums agreed exactly.

Another question was asked and satisfactorily answered. Before two other gentlemen he gave the amount of nine figures multiplied by nine. ... In 1790 he died at the age of 80 years, having never learned to read or write, in spite of his extraordinary power of calculation.

It is astonishing with what facility the African brokers reckon up the exchange of European goods for slaves. One of these brokers has ten slaves to sell , and for each of these he demands ten different articles. He reduces them immediately by the head to bars, coppers, ounces... and immediately strikes the balance. The European, on the other hand, takes his pen, and with great deliberation, and with all the advantage of arithmetic and letters, begin to estimate also. He is so unfortunate, as to make a mistake: but he no sooner errs, than he is detected by this man of inferior capacity, whom he can neither deceive in the name or quality of his goods, nor in the balance of his account.

It is best I got no learning; for many learned men be great fools.