Quadratic fields with large 3-rank (Invited Talk), ICSFA-2023, Pondicherry University, Pondicherry, November 02-04, 2023. 

On a class of Lebesgue-Ramanujan-Nagell equations (Invited Talk), Kerala School of Mathematics, Kozhikode, Kerala, July 21, 2023.

A conjecture of Iizuka (Invited Talk), 16th International Conference on Number Theory and Related Problems, Northwest University, Xi'an, China, May 19--22, 2023.

Simultaneous divisibility of class numbers of quadratic fields (Invited Talk), IECYRANT-2023, University Sidi Mohamed Ben Abdellah, Fez, Morocco, January 12-13, 2023. 

On a Conjecture of Iizuka (Invited Talk), ICSFA-2022, Mysore University, Mysuru, India, November 26--28, 2022. 

Families of quadratic fields with 3-rank at least 3 (Invited Talk), Kerala School of Mathematics, Kozhikode, Kerala, August 02, 2022.  

On a Conjecture of Iizuka (Invited Talk), Kerala School of Mathematics, Kozhikode, Kerala, August 01, 2022.  

Mathematics, mathematicians and career opportunities (Invited Talk), SCIFIESTA-22, Nowgong Girl's College, Nagaon, Assam, March 14, 2022.

Parameterized families of quadratic fields with large $n$-ranks (Invited Talk), International Number Theory Conference, Xi'an Technological University, XI'an, Shaanxi, China, July 03--05, 2021.

A correspondence between binary quadratic forms and quadratic fields (Invited Talk), Institute of Mathematics and its Applications, Bhubaneswar, Odisha, India, July 02, 2021.  

Quadratic fields with small class groups and some conjectures (Colloquium), Shandong University, Wei Hai, China, May 24, 2019.

Mersenne primes  and more (colloquium), Northwest University, Xi'an, Shaanxi, China, May 23, 2019.

Lebesgue-Ramanujan-Nagell type equations (Invited Talk), The 15-th International Conference in Number Theory and Related problems, Hetao University, Bayannaoer, China, May 16--19, 2019.

Closed form expressions for Dedekind zeta values (Invited Talk), The International Conference on Special Functions & Applications, Amal Jyothi College of Engineering, Kanjirappally, Kerala, India,  November 22--24, 2018. Slides

Real quadratic fields with class numbers 1, 2 and 3 (Colloquium), Mahidol University (IC), Bangkok, Thailand, November 07, 2018. Slides

Real quadratic fields with small class number (Invited Talk), The 11-th International Conference on Mathematics and Mathematics Education for Developing Countries, The National University of Laos, Vientiane, Laos, November 02--04, 2018.

Pell-type equations and class groups of cyclotomic fields (Colloquium), Shaanxi Normal University, Xia'an, Shaanxi, Chian, April 12, 2018. 

Pell-type equations and class numbers of cyclotomic fields (Colloquium), Northwest University, Xi'an, Shaanxi, China, April 11, 2018.

Exponents and class groups of quadratic fields (Invited Talk), The 14-th International Conference in Number Theory and Smarandache problems, Northwest University, Xi'an/Yangling, China, April 05-07, 2018. 

On class groups of quadratic fields (Colloquium), Mahidol University (IC), Bangkok, Thailand, November 13, 2017.  

An analogue of Wilton's formula and some applications (Invited Talk), The Tenth International Conference on Mathematics and Mathematics Education in Developing Countries, Mandalay University, Mandalay, Myanmar, November 10--12, 2017. 

On the class numbers of imaginary quadratic fields (Invited Talk), International Conference on Special Functions & Applications (ICSFA-2017), College of Engineering and Technology, Bikaner, November 02--04, 2017. 

Divisibility of the Class Numbers of certain quadratic fields (Colloquium), University of Hong Kong, Hong Kong, March 31, 2017. 

Divisibility of the class numbers of some real quadratic fields (Invited Talk), The 13-th International conference in Number Theory and Smarandache problems, Shangluo University, March 24--26, 2017. 

Divisibility of Class Numbers of Certain Number Fields (Institute Talk), Harish-Chandra Research Institute, Allahabad, India, January 31, 2017.

The Class Numbers of Certain Number Fields (Invited Talk), Two day--Number Theory Meet, (Occasion Prof. Michel Waldschmidt's 70-th birthday), Harish-Chandra Research Institute, Allahabad, India, September 7--8, 2016.

Delivered a talk on "Divisibility of Class Numbers of Quadratic Fields (Institute Talk), Harish-Chandra Research Institute, Allahabad, India, April 27, 2016.

On the divisibility of the class numbers of certain real quadratic fields, 82nd Annual Conference of the Indian Mathematical Society, University of Kalyani, Kolkata, India, December 27--30, 2016.

Continued fractions and Gauss conjecture on class numbers, National Conference on Advances in Mathematical Sciences, Gauhati University, Guwahati, India, December 22--23, 2016.

Solvability of diophantine equations and class numbers of related quadratic fields, National Seminar in Advances in Mathematical Sciences, Gauhati University, Guwahati, India, December 21--22, 2015.

On conjugate quadratic fields whose class numbers are divisible by 3, International Conference on Frontiers in Mathematics, Gauhati University, Guwahati, India, March 26--28, 2015.

On the Class Numbers of Quadratic Fields whose Discriminants are multiple of exactly primes, National Conference on Recent Trends of Mathematics and its Applications, Rajiv Gandhi University, Arunachal Pradesh, May 26--27, 2014.

On the generalized Mersenne primes $p^q-p+1$, Recent trends in Mathematics & its Applications, Digboi College, Digboi, India, October 07--08, 2013.

A family of imaginary quadratic fields whose class numbers are multiple of three, National Conference on Pure and Applied Mathematics, Royal School of Engineering and Technology, Guwahati, India, May 09--10, 2013.

Quadratic fields with class number divisible by 3, 78th Annual Conference of the Indian Mathematical Society, Banaras Hindu University, Varanasi, India, January 22--25, 2013.