Gradually, over the years, Shakuntala's memorizing and calculating skills were strengthened, whilst she simultaneously became an expert in complex mental arithmetic. Beginning at the University of Mysore and the Annamalai University, Shakuntala's public displays of her extraordinary abilities and talents even spread to institutions worldwide, bewildering the crowded gathering of students and professors alike. In her time, older calculating prodigies like Truman Henry Safford were also present, yet Shakuntala started displaying her talents from a very young age.
With her brilliant mind, Shakuntala Devi was adept at solving arithmetical problems, including functions of addition, multiplication, division, calculating square and cube roots, along with complex algorithms and Vedic Maths. She could even state the day of the week of any given date in the last century in a jiffy. Shakuntala could even outdo some of the fastest available computers of that period. Amongst her numerous feats, the most outstanding ones that fetched her name in the 1995 Guinness Book of World Records are:
- In January 1977, at the Southern Methodist University in Dallas, Texas, Shakuntala Devi extracted the 23rd root of a 201-digit number, at the fifty-second mark, with the correct answer being '546372891'. She had beaten the then fastest computer, UNIVAC's time of 62 seconds, and 13,000 instructions.
- On 18th June, 1980, Shakuntala Devi demonstrated the multiplication of two 13-digit numbers: '7,686,369,774,870 x 2,465,099,745,779', picked randomly by the Computer Department of Imperial College, London. She produced the correct answer of '18,947,668,177,995,426,462,773,730', in just 28 seconds.
- Shakuntala could find the cube root of 332 812 557 in under a minute.
Today Shakunatala Devi is an accomplished mathematician whose interests also include the mystic field of Astrology. While setting up of several mathematics research centers are her future plans, Shakuntala Devi has also written numerous books, some of which are - Puzzles to Puzzle You, Fun with Numbers, Astrology for you and Mathablity.