On July 30th, Shandong University held a commemorative ceremony for the 90th anniversary of the birth of Mr. Pan Chengdong. As a mathematician, this name appeared in the reportage "Goldbach Conjecture" by writer Xu Chi. Pan Chengdong, a lecturer at Shandong University, has successively proved the propositions of "1+5" and "1+4" in the study of Goldbach's Conjecture. At that time, Pan Chengdong was not yet 30 years old. Due to his leadership in the study of world problems twice, known as the "pearl on the crown of mathematics", he, along with Hua Luogeng, Chen Jingrun, and Wang Yuan, is recognized by the international mathematical community as one of the four outstanding representatives of the Chinese number theory school; He, together with Chen Jingrun and Wang Yuan, won the first prize of the the State Natural Science Award. In 1991, he was elected a member of the Academic Department of the Chinese Academy of Sciences (now called an academician). Achievement comes from obsession and focus. As his family said, "All day long, he only knows how to sit in the study and conduct research." Young Pan Chengdong was passionate about mathematics, and in 1952, he was admitted to the Department of Mathematics and Mechanics at Peking University with excellent grades. Under the guidance and influence of renowned scholars such as Hua Luogeng and Min Sihe, he made mathematical research his lifelong pursuit. In 1961, after graduating from Peking University as a graduate student, he joined the Mathematics Department of Shandong University as a teacher. Over the past 30 years, he has taught more than 10 courses including mathematical analysis, advanced mathematics, theory of real functions, and Goldbach's conjecture. At the end of 1997, Pan Chengdong, who was only 63 years old, unfortunately passed away. Wang Yuan, a close friend, was deeply saddened. In his article "Memories of Pan Chengdong," he wrote, "Chen Jingrun has only been gone for over a year, and Pan Chengdong has left again..." Wang Yuan cannot forget the correspondence and discussion between Pan Chengdong and him on academic issues. He wrote me a lot of letters, constantly telling me his results... I didn't believe in Chengdong's results, and every time he refuted them, Chengdong explained and wrote to each other for a long time. In the end, in an indisputable situation, I still admitted Chengdong's' 1+5 '. During this period, Chengdong wrote me more than sixty letters in total, while he only wrote about two letters to his fianc é e Shuying, which shows his intense struggle. "Pan Chengdong's departure left the students in deep sorrow. When bidding farewell to the gentleman, a row of young scholars from all over the world stood solemnly. Most of the doctoral and master's students guided and trained by Mr. throughout his life have become the backbone of number theory research in China. Opening Pan Chengdong's photo album, time seems to unfold again. There are black and white photos from before the 1980s: a photo of him with Hua Luogeng, and a photo of him with Chen Jingrun and Wang Yuan. When I was studying at Shandong University, Master Pan once invited four digit theorists Hua Luogeng, Ke Zhao, Chen Jingrun, and Wang Yuan to come to the school together, so that all the students in the school could see the mathematical legend that they had admired for a long time. Chen Jingrun and Wang Yuan also attended my senior brother Yu Xiuyuan's doctoral thesis defense at Shandong University, which greatly inspired the entire school, especially the students in the Mathematics Department Professor Cai Tianxin from the School of Mathematical Sciences at Zhejiang University recalls. In the photo, Pan Chengdong is over 1.8 meters tall and extremely thin. During those difficult years, he remained unmoved by the storms and silently persisted in his mathematical research, to the point of being physically and mentally exhausted. Doing a paper is the most tiring "" Sometimes at the end of the day, I am so tired that I don't even have the strength to speak "... Students always think of their teacher's words, his resolute gaze, and the image of him tirelessly studying despite extreme fatigue. A seed has been planted in the hearts of the students: pure research only shows the most enchanting magic to those who tirelessly explore. There are also photos from the 1980s onwards: the spirited teachers and the growing 'future mathematicians'. Zhan Tao, the current director of the UNESCO Institute for Information Technology in Education, still remembers the anxiety he felt when he first went abroad and entered the international circle of number theorists. However, when he introduced himself as "Pan's student", he immediately received a friendly gaze. At the moment when Richard, a famous German mathematics professor, said, 'You have a good teacher,' Zhan Tao felt immensely proud and happy. What the students saw from Pan Chengdong was one breakthrough after another: he first obtained a quantitative estimate of the upper bound of the minimum prime number in arithmetic sequences, which was widely cited and used as a theorem; He was one of the earliest scholars to participate in the International Conference on Analytical Number Theory after the reform and opening up, and opened a new door for communication and cooperation between China and the international number theory community with a one hour report; He applied his established mean estimation to the study of the Goldbach Conjecture and made a series of breakthrough progress; He and his younger brother Pan Chengbiao wrote the world's first comprehensive and systematic monograph on the study of the Goldbach Conjecture, "Goldbach Conjecture"... Teacher Pan Chengdong has an extremely distinctive teaching style. He has always valued the word 'strict'. During his college years, Pan Chengdong participated in a "Goldbach Conjecture" discussion class, where each unit was usually taught by one person. Teachers such as Hua Luogeng kept asking questions to ensure that students fully understood every point, which put a lot of pressure on them but benefited them greatly. Pan Chengdong applied this method in his teaching: in class, he often asks questions, and students cannot sit down until someone answers. Only then do he allow standing students to sit down. He has always advocated for a 'big picture approach'. In the memory of students, Pan Chengdong's lectures often go straight to the point - without getting entangled in details, focusing on explaining the origin and development of the problem and the ideas contained therein, analyzing the development, methods, and results of the theoretical system, and taking a unique approach. He encourages innovation and exploration the most. Students remember his advice: to tackle big problems and explore new fields. He once said that the level of writing is not directly related to the position, and the best paper he wrote was completed when he was a lecturer. Young people should have more spirit, be brave in researching new topics, and explore 'no man's land'. Thanks to such academic guidance, his students today occupy the international academic high ground in both number theory and cryptography. Dr. Yu Xiuyuan, a 1983 PhD student, was one of the first 18 PhDs in New China and grew to surpass experts in number theory and cryptography. His book "Estimation of Order" co authored with Pan Chengdong is currently the only specialized textbook in China that discusses order estimation methods. Dr. Wang Xiaoyun, born in 1993, is a representative figure in the field of cryptography. In the late 1980s, Pan Chengdong was sharp and forward-looking, and suggested that Wang Xiaoyun change his main focus to the application of number theory in cryptography. Since then, Wang Xiaoyun has overcome many difficulties in the field of cryptography and was elected an academician of the CAS Member. Dr. Zheng Zhiyong, born in 1991, made breakthrough contributions in the fields of geometric theory of exponential and characteristic sums, as well as analytical theory of functional domains; In 1995, Dr. Liu Jianya applied high-dimensional self preservation forms to prime number distributions and achieved a series of important results... Teacher Pan Chengdong also has an interesting side. He is familiar with history, loves reading martial arts novels, plays good chess and bridge, and is also a key player in the Peking University table tennis team. Liu Jianya, Vice President of Shandong University, deeply understands Pan Shi's painstaking efforts: mathematical research is a purely intellectual creative process, and breakthroughs are often triggered by seemingly unrelated factors. Therefore, Pan Shichang encourages students to go out and communicate with different people, generating inspiration through collisions. Principal Pan Chengdong, the growth of a university is the result of his hard work, and the abundance of students and talents throughout the world is his pride. During his tenure as the head of the Department of Mathematics at Renshan University, Pan Chengdong planned the development path of the discipline with high standards, emphasizing both teaching and research. Today, the school has developed into a mathematics research center with significant influence both domestically and internationally; As the president of Shandong University, he advocates for the development of both arts and sciences, and the integration of new and old disciplines. While developing existing key disciplines, he actively supports the construction of high-tech disciplines, laying a solid foundation for optimizing the layout of disciplines. He proposed the strategy of strengthening schools through talent earlier in China, breaking conventions and emphasizing the importance of talent. In 1987, he made a decision to prioritize the allocation of housing for young teachers with doctoral degrees. In 1992, he presided over the launch of the "Unconventional Professor" program, which allowed teachers under the age of 40 to be promoted to the professorship without occupying the quota of their department, and were uniformly screened by the school. To this day, people still often tell his stories and encounter him time and time again: walking past his bronze statue, stopping at the Pan Chengdong Mathematics Research Institute, and paying attention to the list of winners of each Pan Chengdong Scholarship... Ren Youqun, Secretary of the Party Committee of Shandong University, and Li Shucai, President, wrote in the preface of "Pan Chengdong Photocopying Collection": Mr. Pan Chengdong is a model scientist who is tenacious and brave in climbing new heights, a model of a great gentleman who is willing to serve as a ladder and reward future studies, and a model educator who learns from the past and pursues excellence. Sir's soul, never far away; A sincere heart, never far away! (New Society)