--- title: "Shakuntala Devi found the 23rd root of a 201-digit number in 50 seconds, while a computer took 62" url: https://badiyaa.com/shakuntala-devi-23rd-root-201-digit/ published: 2026-11-13T11:48:00+00:00 modified: 2026-11-13T11:48:00+00:00 section: History publisher: Badiyaa --- # Shakuntala Devi found the 23rd root of a 201-digit number in 50 seconds, while a computer took 62 Shakuntala Devi, India's Human Computer, found the 23rd root of a 201-digit number in 50 seconds in 1977; a UNIVAC 1101 needed 62. In 1977, at Southern Methodist University in Dallas, Shakuntala Devi was given a 201-digit number and asked for its 23rd root. She answered 546,372,891 in about 50 seconds. The machine brought in to confirm it, a UNIVAC 1101 at the US Bureau of Standards, needed a specially written program and 62 seconds to agree with her. That single afternoon goes a long way toward explaining why India’s most famous mental calculator was billed as “the Human Computer.” The numbers still hold up when you check them today. ## A circus childhood in Bangalore Devi was born in Bangalore on November 4, 1929. Her father, C. V. Sundararaja Rao, was a circus man who did trapeze, tightrope, lion taming and magic. While teaching her a card trick when she was around three, he saw that she could hold numbers in her head with ease. He quit the circus and put her on the road instead of in a classroom. By six she was performing arithmetic for an audience at the University of Mysore, still with no formal schooling. In 1944, aged 15, she moved to London, and for decades afterward she toured the world, including Europe in 1950 and New York in 1976. ## Checking the 201-digit root A 23rd root asks a simple question with a brutal answer: which number, multiplied by itself 23 times, gives the target? Badiyaa reran the arithmetic with exact integers. Raising 546,372,891 to the 23rd power gives a number precisely 201 digits long that starts 916,748,676,920. The length alone narrows the search. Any nine-digit number from 100,000,000 upward, raised to the 23rd power, has at least 185 digits, and one close to 999,999,999 reaches 207. A 201-digit target therefore forces a nine-digit answer in the upper half of that range. Fixing every one of those nine digits in under a minute is the part nobody else could do. Devi set out many of her techniques in her 1977 book Figuring: The Joy of Numbers. ## The Imperial College record Her best-known record came on June 18, 1980. The Department of Computing at Imperial College London chose two 13-digit numbers at random, 7,686,369,774,870 and 2,465,099,745,779. Devi multiplied them in 28 seconds and gave 18,947,668,177,995,426,462,773,730. Our exact recalculation produces the same 26-digit product. The result entered the 1982 Guinness Book of World Records. The certificate took far longer to arrive: it was presented on July 30, 2020, seven years after she died. Writer Steven Smith judged the result “so far superior to anything previously reported that it can only be described as unbelievable.” ## Tested at Berkeley In 1988 Arthur Jensen, an educational psychologist at the University of California, Berkeley, put her through a set of tasks. One task asked for 61,629,875’s cube root; another wanted 170,859,375’s seventh root. She called out 395 and 15 before he had finished copying the problems into his notebook. Both are right: 395 cubed is 61,629,875, and 15 to the seventh power is 170,859,375. Jensen reported his findings in the journal Intelligence in 1990. Badiyaa’s History desk has also traced how [Benjamin Banneker put his mathematics to work surveying Washington, D.C.](https://badiyaa.com/benjamin-banneker-surveyor-washington-dc-boundary-stones/), and how [an English town crier earned a Guinness record for the loudest shout by a woman](https://badiyaa.com/brenda-willison-town-crier-loudest-shout-woman-record/). ## Beyond the numbers Devi also wrote puzzle books, cookbooks, crime novels and astrology guides. Her 1977 book The World of Homosexuals is regarded as the first study of the subject in India, and it closed with a call for decriminalization. In 1980 she even ran for India’s parliament without a party. A biographical film starring Vidya Balan premiered worldwide on July 31, 2020, and Google honored her with a Doodle on November 4, 2013, which would have been her 84th birthday. ## Further reading - [Wikipedia: Shakuntala Devi](https://en.wikipedia.org/wiki/Shakuntala_Devi) *Image: Carol M. Highsmith, Public domain via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*