The builder of Thang Long citadel gate did not leave a single brick to spare.

He is considered the first mathematician of Vietnam, a famous mandarin during the reign of King Le Thanh Tong, famous for his accurate calculation of brick numbers to build Thang Long citadel.

The person mentioned is Vu Huu (1437-1530) from Binh Giang district, Hai Duong province today.

According to historical records, as a child, due to poverty, Vu Huu was not able to go to school but soon showed a special talent for Mathematics. When the villagers wanted to repair the dilapidated communal house, the village elders were confused and did not know how to calculate to complete the house. The young Vu Huu only needed to look at it, then used a stick to draw on the ground to calculate, and in a moment it was done. The construction workers did exactly as Vu Huu did, and indeed, everything was correct. Everyone was surprised and praised Vu Huu as a prodigy, from then on the whole village contributed money to support his education.

In the year of Quy Mui (1463) under the reign of King Le Thanh Tong, he passed the royal examination (a title of Confucian doctorate in the feudal examination system) at the age of 20, then became an official, reaching the position of Minister of the Ministry of Finance.

Passionate about Mathematics, Vu Huu systematized the achievements of geometry and arithmetic at that time, wrote the book Lap Thanh Toan Phap, giving specific and precise instructions on how to divide land, build houses and ramparts. This is the first book specializing in mathematics in our country.

Vu Huu left behind the work "Establishing a Mathematical Law", which gave specific and accurate instructions on how to divide land among the people. (Illustration photo)

The book "Telling the Story of a Vietnamese Mandarin" records that at that time, King Le Thanh Tong saw that the gates of Thang Long citadel built during the Ly Dynasty were badly damaged, so he wanted to rebuild them. Several mandarins were assigned to measure for a long time, but after a whole month they still could not calculate the number of bricks needed to build the citadel. Knowing Vu Huu's talent for calculating and measuring, the king sent him to estimate the number of bricks needed to build the citadel.

After finishing the measurement, he told the king: "I have calculated carefully, not a single brick is too big or too small." An official expressed doubt and put him in a difficult position: "In that case, please make a commitment, if there is any discrepancy, you will be punished."

King Le Thanh Tong asked: "If the officials have such an idea, do you dare to accept it?" Vu Huu replied: "Your Majesty, I accept your idea."

Vu Huu then ordered someone to buy bricks and stack them neatly by the city gate. When the job was completed, the official looked pleased: "Your Majesty, there is still one brick left here."

Vu Huu held the brick and calmly said: "Your Majesty and ministers, this brick is not redundant. On the east wall over there is a broken brick, I have specially ordered this brick to replace it."

Everyone was half-believing, half-doubting, Vu Huu led the king to the other side of the wall, ordered the workers to climb up to remove the broken brick and put in a new brick that fit perfectly. King Le was very pleased and issued a decree of reward, everyone was amazed and admired Vu Huu.

Libra

Source: https://vtcnews.vn/ky-tai-dat-viet-nguoi-xay-cong-thanh-thang-long-khong-thua-mot-vien-gach-ar925639.html