Durgapur, June 3: Mainak Sarkar was so fascinated with mathematics that he used to solve problems on every wall in his home, even in the bathroom.

"Not only the walls, even the bed sheets were filled with mathematical problems and their solutions, scribbled with a pen," said Utpal Majumdar, recounting the first time he had entered the 580sqft flat in Durgapur where Mainak and his elder sister grew up.

Majumdar, a retired railway employee, had bought the flat from Mainak's father in 2004.

"I used to offer private tuition to school students in mathematics and so I could understand that only someone who had a thorough command over the subject could work on the problems that were scribbled on the wall. It was as if the walls were Mainak's blackboard," added Majumdar.

What Majumdar saw reminded the private tutor of the 2001 film A Beautiful Mind, in which Nobel laureate John Nash is shown working on mathematical problems on windowpanes.

Majumdar had bought the flat at R-II/20 in Durgapur's Bidhan Nagar from Mainak's father Satyen after the IIT alumnus had moved to the US.

Mainak's mother had died in the early 2000s, "heartbroken" that her son had moved abroad.

"Satyen Sarkar was staying alone in the flat as his daughter Soumi, a chemical engineer, had married and was living in Calcutta with her husband. So he decided to sell the flat and move into an old-age home at Jadavpur in Calcutta, close to his daughter's home," said Majumdar's wife Champa.

After moving to the city, Satyen, who had taken voluntary retirement from his job in the administrative wing of a Durgapur factory, used to return to the flat where his children had grown up.

"He was emotionally attached to the flat because of the memories associated with it. While chatting with me during one visit, he spoke of his son's fascination with mathematics," said Majumdar.

According to Champa, Satyen died about a year-and-a-half ago in a train accident during one such trip between Calcutta and Durgapur.

The Majumdars learnt about Mainak from neighbours on Friday afternoon.

"We don't watch TV much and don't follow the newspapers regularly," said Champa, sitting in the 2BHK flat on the first floor of a three-storey building.

In the modest neighbourhood, Mainak's name was on everyone's lips on Friday.

As they discussed his "tragedy", they also mentioned another gruesome crime in the area.

In a block adjacent to R-II, bank manager Samaresh Sarkar had in August last year allegedly murdered and chopped up Sucheta Chakraborty, another resident of the colony who lived with her daughter, because she had threatened to expose their extramarital relationship and approach police if he refused to marry her.

Mainak's fascination with mathematics was also corroborated by Sumon Sarkar, who lives on the top floor of the building.

Sumon and Mainak had both passed the ICSE in 1994. While Sumon passed out from St Xavier's, Durgapur, Mainak cleared Class X from St Michael's School, Durgapur.

Having resided in the same building, Sumon had seen Mainak from close quarters.

"He would love to remain absorbed in mathematics. He was an introvert. But brilliant students, I suppose, have to be introverts. There's too much going on in their head. I am shocked to learn about his tragedy," said Sumon, who works in a tech firm in New Town.

Sumon's mother Hena Sarkar said Mainak was so much of an introvert that he would not let anyone photograph him.

"My husband had a passion for clicking photographs. But whenever he approached Mainak to take a photograph, the child would run away," said Hena.

Years later, in the US, he appeared to have shed the aversion. Mainak's Facebook page had several images of him posing for pictures with his wife Ashley Hasti.

Both Sumon and Mainak passed their HS exam from the same school, Bidhan Chandra Institution, in Durgapur in 1996.

Ujjal Sarkar, the principal of Bidhan Chandra Institution, said Mainak had scored 715 out of 1,000 marks in the HS exam.

After that, Sumon took admission to NIT Durgapur, which was then known as RE College. Mainak got through to IIT Kharagpur in aerospace engineering.

Goutam Biswas, a teacher at St Michael's, recalled that from Class VII onwards, Mainak used to dream about studying at IIT Kharagpur.

"I taught him from Class VII to X. Mainak was always in the top 10 in his class. From the beginning, he had been very focused on studying at the IIT. His solid grounding in mathematics helped him realise his dreams," said Biswas.

The untimely death of Mainak has left St Michael's alumni shocked.

Sumita Mukherjee, the alumni secretary, said they had had plans to get in touch with outstanding students like Mainak on the occasion of St Michael's golden jubilee this year.

"We have already contacted some of the prominent alumni. Mainak was also on our list. But who would have thought that Mainak was going to meet with such a tragedy," said Mukherjee.

Mukherjee was the personal assistant to the then principal when Mainak had passed his Class X board exams.