Mathematician Le Ba Khanh Trinh: 'My students have lifted me up'

Dr. Le Ba Khanh Trinh and the Vietnamese team of students and teachers attending IMO 2025 - Photo: G.D.

Mathematician Le Ba Khanh Trinh was called "the golden boy of Vietnamese mathematics" when he was a student. Later, when he became attached to the profession of white chalk and blackboard, many generations of students gave him the nickname "the legend of Vietnamese mathematics". He has just received a retirement decision from the Gifted High School (Ho Chi Minh City National University).

In a conversation with Tuoi Tre reporter, he confided: 'Many people keep saying that I lift up my students, but it is they who lift me up, motivate me, and inspire me to renew myself every day'.

From the book "treasure"

* Let's start the story with the milestone of 1979: how did he do the test to get the perfect score (won the gold medal) and the special prize for unique solution in the International Mathematical Olympiad (IMO)?

- In grade 10 at Quoc Hoc High School for the Gifted in Hue , I was lucky to find a book about geometry from a very new perspective. Basically, before that, I often learned about transformations in geometry in a "static" way, but this book explained it in a "dynamic" way, more interesting, more modern and simpler.

I have considered this book as a treasure. Throughout my high school years, I not only studied the book but also received dedicated guidance from my teachers. This made me increasingly imbued with the book's ideas.

Le Ba Khanh Trinh received the international mathematics gold medal in 1979 - Photo: G.D.

In grade 12, in 1979, I was one of the Vietnamese students who participated in the IMO in England. The exam had three problems with a time limit of 270 minutes.

After finishing, with 20 minutes left to check my answers, I discovered that I had gotten off topic in problem number 3, which was geometry. The test gave two circles and two points moving in opposite directions, but I mistakenly read them as moving in the same direction.

If time is allocated, each problem needs an average of 90 minutes to solve. In an urgent situation, with only 20 minutes left, I chose the shortest solution according to the spirit of the book I had studied.

This solution made the judges give me the special prize as everyone knows.

* Sir, many talented people have chosen to stay abroad to start their careers. Why did you choose to return after graduating with a PhD in mathematics in Russia?

- Many people have asked me whether I chose to return to contribute my efforts and intelligence to my country. I do not want to mention such lofty words. I chose to return because I consider it a natural thing, my family and relatives are in Vietnam, so I return to Vietnam.

Moreover, at that time the country was opening up with many positive changes. I was easily accepted into the Mathematics Department of Ho Chi Minh City University of Science (now the University of Natural Sciences , Vietnam National University, Ho Chi Minh City) and was given the best working conditions.

Then the Gifted High School was established and I was assigned to be in charge of the math department there.

Teacher Le Ba Khanh Trinh and 2 students from Gifted High School won gold medals at IMO 2013: Pham Tuan Huy (left cover), Can Tran Thanh Trung (right cover) - Photo: G.D.

* Not only did you leave your mark by directly leading the math team of the Gifted High School, but you also directly led the Vietnamese math team to many outstanding achievements. Surely you have many special memories?

- Up to now, Vietnam has participated in IMO for more than 50 years. With the Vietnamese team, I have only been with the students for more than ten years.

In 2013, I was the first time I led a team to the IMO. That year, the Vietnamese team won three gold medals and three silver medals, all six participating members won medals, and the total score ranked seventh out of 97 participating teams. However, I still regretted that I did not have much experience and I learned my lesson right away.

In 2017, the students gave us the biggest surprise. After the first day of the exam, most of the students said they did not do well, we encouraged them to try their best, there was still a second day.

After the exam, I reviewed the test and saw that the students did very well. In fact, some students did not do well on the first day of the exam but then made an extraordinary effort on the next day. That year, Vietnam won four gold medals, one silver medal, and one bronze medal - ranking third out of 112 countries, behind only China and South Korea, surpassing the US and Iran.

In 2022, when the world had just experienced the COVID-19 pandemic, this year's IMO results made us burst into tears when Ngo Quy Dang was named with the maximum score of 42/42 points.

The moment of honor and award ceremony, seeing my students carrying the red flag with yellow star walking on stage (students with maximum scores are honored individually, not in groups), I felt an indescribable pride and emotion. This was also an impressive moment that I can never forget.

Associate Professor Dr. Vu Hai Quan, Director of Ho Chi Minh City National University (middle), presented the National University's commemorative medal to Mr. Nguyen Thanh Hung (right cover) and Mr. Le Ba Khanh Trinh (left cover) - Photo: provided by the school

Bring each lecture to life

* Students of the Gifted High School once showed off on social media a clip of Mr. Trinh dancing along with students singing the song "Chalk Dust" in a very humorous and cheerful way.

- The tradition at Gifted High School is that during teaching hours near Vietnamese Teachers' Day, students will sing for their teachers.

When students express their feelings, I also need to do something to interact with them, I cannot just sit and enjoy. So to create a fun and friendly atmosphere, I dance and clap my hands, or if the class is equipped with a guitar, I play the guitar to accompany the students to sing.

When I teach, I am very serious and not joking around like that. But I want to make my students laugh a lot, so instead of speaking normally, I change it to be more witty and humorous.

* Many generations of students have commented that Mr. Trinh teaches math very inspiringly and easily. Surely he has his own principles in teaching?

- My educational background comes from my math teachers in Russia. I learned from them that sometimes a problem is difficult, but if you draw a picture and analyze it further, it will be easier for students to understand.

After drawing the picture, sometimes students are surprised at how simple the problem is. Therefore, during class I never sit in one place, I have to walk up and down, back and forth, point here and there, draw pictures so that students can understand the problem...

But I don’t copy what I have learned, I monitor my students’ reactions to adjust my teaching methods. At first, when I had no experience, I chose what I thought was the best lesson from someone else and gave it to my students to solve.

I thought that the solution to that problem was great. But it was the students who made me "enlightened". They had many creative solutions that I did not expect.

And I realized that taking other people's work would be dry and lack my own soul. It was the students who motivated me to change. I practiced creating questions and presenting them in my own way, practicing making my work more soulful.

Especially with those problems, the students accepted them enthusiastically, which made me feel like I was fueled with "professional fire". I felt that I had to constantly learn and be creative so as not to be passive in front of my students.

Mr. Le Ba Khanh Trinh's family - Photo: G.D.

Still accompanying students who love math

* Now that you have received the decision to retire, is there anything you are still worried about that you have not been able to do?

- Before, I used to dream of enjoying a rural life when I retired, just a small house in a peaceful countryside somewhere, reading books, planting trees, playing the guitar every day... But I still owe a lot of gratitude, so I can't enjoy that pleasure yet.

Retirement is just an administrative decision. In the future, I will continue to accompany students who are passionate about mathematics at the Gifted High School and some other provinces.

I also want to have a piano so that I can play it my way when I want. But that would require a really big room. My current house is a bit small…

In addition, I also intend to write a set of documents to systematically cover all mathematical problems after years of training excellent students, but this has not been done yet.

* Back to the story of studying abroad and returning. After 35 years of returning home, are you satisfied with your current job and life?

- Nowadays, every day I go to school is still full of excitement, that I will launch a new "trick" for the students and I also eagerly wait to see what surprises they will bring me.

I consider this a blessing because I have the opportunity to interact with and teach the country's elite students. Many people say that I elevate my students, but it is they who elevate me, motivate me, and inspire me to renew myself every day.

To be honest, when I stand on the podium, I am very excited, very optimistic, very happy. It's just that when I lock myself in my room, "plowing" the lesson to make it soulful, to make it enthusiastically received by students... sometimes I feel tired.

* In the media, people only see Dr. Le Ba Khanh Trinh talking about his passion for mathematics, but his private life...

- During my years in college, graduate school and then as a PhD student in Russia, most of my friends had lovers, but I was shy so I didn't have any.

I returned to Vietnam in 1990 and got married in 1998. My wife works in the banking industry. My eldest daughter just graduated from Ho Chi Minh City University of Architecture with a degree in graphic design. My youngest son followed his mother's career and has just finished his first year at Ho Chi Minh City University of Banking.

As far as material life is concerned, I have nothing to complain about. With the extra money, I sometimes find myself wasting time thinking about how to handle it.

Never give students zero points

Not only do I want to surprise my students, I also want them to improve every day. So in over 30 years of teaching, I have never given a student a zero in my notebook. I will give any student who gets a zero a chance to erase the zero by volunteering to go to the board to solve difficult math problems. There are even students who started with a zero and ended up getting the most 10s in the class.

I also do not force students to do all my exercises, whoever can do it, I invite to come to the board. There are difficult problems, sometimes the whole class is not confident and hesitates, at that time, if a student dares to go to the board, I immediately give 10 points. This is 10 points for boldness and confidence.

"I like playing the guitar"

Le Ba Khanh Trinh in a moment of improvisation playing guitar with friends - Photo: G.D.

* I heard you are a great guitar player?

- I like playing the guitar. My family used to have a guitar. Last time, on my birthday, my wife gave me another one (laughs). And it was good for her because I often play for her.

I recently surprised my wife by connecting my guitar to an amplifier - the sound was much better than usual (laughs).

Go shopping for the whole family

* I heard that you are the "main member" who goes shopping for the whole family? How do you teach your children?

- (laughs) Actually, I just go to the supermarket. I did these things regularly when I was studying in Russia, so when my wife and children are busy, I go to the market for my wife, it's normal.

At home, I usually only cook European dishes, while my wife cooks traditional Vietnamese dishes. My wife's job is quite tiring, working at the bank from morning to evening, so when I'm home, I cook rice, wash dishes, clean the sink, take food out of the refrigerator... so that when my wife comes home in the evening, she only has to cook, which makes her less tired. That said, there are times when I'm stuck in my room working on math problems and I forget...

At home, my wife and I have slightly different views on raising our children. I want to discipline them with iron discipline, in the same harsh direction as I did in the past. My wife is more indulgent and easy-going with them.

I'm not sad that my children don't follow my career path because the world is so open now. But sometimes I think back, I wonder if it's because I'm so poor that my children are afraid, and none of them dare to follow their father's career path (laughs).

HOANG HUONG

Source: https://tuoitre.vn/nha-toan-hoc-le-ba-khanh-trinh-hoc-tro-da-nang-toi-len-20250812091156087.htm