A MATH wizard from Bangalore, India, by the name of Shakantula Devi made it to the Guinness Book of Records in 1980 when she mentally multiplied two 13-digit numbers in 28 seconds. This was the arithmetic operation she performed:
7,686,369,774,870 x 2, 465,099,745,779 = 18,947,668,177,995,426,773,730
Since then, Ms. Devi had routinely beaten sophisticated computers right in their own turf. In one such contest, it took her only 50 seconds to get the 23rd root of a 21-digit number, while the computer took over a minute to perform the same job.
Read the full article here: https://www.manilatimes.net/2022/10/06/campus-press/the-grammar-of-numbers-and-time/1861151