She never received a formal education, but Shakuntala Devi - India's most remarkable math prodigy - could perform unbelievable calculations in her head in seconds.
Devi, who has died aged 83, was so good at numbers that it was "like a native language," according to educational psychologist Professor Arthur Jensen.
Just how good was she? Well, the computer department at Imperial College, London tested her skills in 1980, asking her to multiply two random 13-digit numbers (7,686,369,774,870 x 2,465,099,745,779).
It took her 28 seconds to get the answer - and that includes the time it took to say the number.
Any guesses? The correct answer was 18,947,668,177,995,426,462,773,730, according to the Telegraph.
That speedy response got her a spot in the Guinness Book of Records, and she performed similar acts of extreme calculation throughout her life.
She appeared on Russia Today in 2009, where she corrected an equation the host gave her, and showed off her skills. Check that out below:
Devi often competed against computers as well. In 1977, she extracted the 23rd root of a 201-digit number in 50 seconds at Southern Methodist University in Dallas. It took a Univac computer 62 seconds to get the same result.
And during an interview with the BBC in the '50s, the host had a different answer than Devi for a math problem. When the calculations were run again, it turns out she was right. The same thing happened during a speaking engagement at the University of Rome.
Devi was born into an orthodox Brahmin family in Bangalore, India, in 1929. Her father was circus performer, who excelled at trapeze, lion taming, tightrope, and the human cannonball.
He first noticed his daughter's math ability when she was three. By five, she could calculate cube roots in her head, and the following year she gave her first public "math performance" at Mysore University.
Because of her father's travel with the circus, Devi never received a formal education. She joined a convent at 10, but was expelled within months because her parents couldn't pay the fees.
She went on to make a living from her mathematical abilities, performing for people around the world.
Professor Jensen, who studied Devi in 1988, said that in addition to her exceptional math skills, she was great with people: "Devi comes across as alert, extroverted, affable and articulate."
And she didn't limit herself to math: she was also a successful cookbook author, novelist and astrologer.
Via The Telegraph