The news about your retirement received a lot of attention. How did you feel about it?

Actually, I officially retired a few years ago. But that was just a procedure on paper because, during that whole time, I was still working, still collaborating with the High School for the Gifted, and continued teaching selected teams of excellent teachers in some places.

Recently, when I felt my health declining, the High School for the Gifted held a gratitude ceremony for my retirement, and that was when the information spread more widely. I accepted retirement with a calm mindset, without regret. The core issue is whether you still care about the work and whether you are still truly useful.

I still do what I did before: I teach students, I do professional work, and I even demand myself to improve further. Now that I have more time, I feel that the quality standard must be even higher.

In 1979, at the IMO in the UK, you won a Gold Medal with a perfect score of 40/40, and also won a special prize for your unique solution. People gave you the title "Vietnam's Golden Boy of Mathematics." What do you think of this title?

Honestly, at that time, I didn't hear anyone call me that. Now I do. Frankly speaking, I only heard the phrase "Golden Boy of Mathematics" in recent years when I'm already a bit older (smiles).

After more than 40 years devoted to teaching, instructing and nurturing many generations of outstanding students, what do you think when you look back at your journey?

That was an arduous journey, but those very hardships gave me a lot of motivation to study and work. I was fortunate to teach and accompany students who were well-behaved, intelligent, and had good foundations and conduct. They were very polite, think maturely, and especially have sharp minds. A large part of my work was successfully completed thanks to the system of gifted schools, which select outstanding students, giving me the opportunity to bond with them, support them, and help them develop.

You said that journey was both arduous and glorious, and although you don't care about glory, many generations of students and colleagues greatly admire you. What are your thoughts?

I don't put too much thought into the word "glory." But subjectively speaking, I think I have suitable motivation, progress, and working environment. 

I don't know if students will still remember me over time, but currently, I feel I have these things. And honestly, those years were thanks to the students: it was them, who gave me the motivation to work. I don't know what that motivation will be like in 10–15 years, but right now, it's still burning like a flame. 

I still work seriously. I believe that meticulousness in work and fairness in treatment are what make people respected.

Nurturing students for international competitions, teaching gifted students,and  teaching at gifted schools, you have interacted with many talented and excellent young people, who can be considered the elite class. What do you feel you have gained from them?

At first, I simply thought that I only needed to introduce interesting math problems without deep elaboration. But very quickly, I realized that the students were so independent that it surprised me.

For the same math problem, many students offered entirely different answers, even contradictory to mine, and I was "stunned" in a positive way. Their knowledge forced me to be sharper, and forced me to change.

From those insights, I began to rewrite the solutions in my own way. The students' excitement towards new solutions gave me extra motivation. Sometimes, students' solutions truly surprised me. Together, silently, we sought the "God's solution", the solution described in textbooks as the most optimal, the most profound, and the most refined. That shared idea makes teachers and students bond, learn from each other, and respect each other, even though it all takes place quietly.

When you teach so many excellent students, do you feel younger? Do you think you are suited to the teaching profession?

Vietnamese students are very hardworking. Each student is a distinct personality, a unique individual, but they strive together when learning. I see the reflection of myself in those quiet, gentle students, like me, who focus intensely during exams and sometimes achieve surprising things.

Thuy Nga