This year's math is particularly simple, that is, the remaining 140 points is a bit difficult. Mathematics is an extremely advanced science (for the general public), but there are always some people in history who are extremely talented in mathematics, such as Han Xin, the "god of war" who lives in the legend. After Han Xin died, he left two classic "math problems", which made many netizens say that they had a headache after seeing it, what is the problem?
Speaking of which, "Han Xin's point of soldiers" should be a historical allusion that everyone is more familiar with, Liu Bang said that the empress dowager was jealous of Han Xin's strength, so he demoted him from the King of Chu to the Marquis of Huaiyin, and summoned him to the palace to accompany him one day. During the banquet, Liu Bang pretended not to care and asked Han Xin, "How many soldiers does the Great General think Shuo can bring?" Although Han Xin was demoted, his speech was still quite straight: "Hold on to 100,000." ”
Liu Bang was very unhappy when he heard this: "How many soldiers can you bring with you, general?" Han Xin smiled confidently: "Of course, the more the better, give me more soldiers, I can also command the dispatch!" Later, the folk had the well-known post-break phrase "Han Xin Dian Bing - The More the Merrier", and then there was a widely circulated mathematical problem:
Han Xin led 1500 soldiers to engage the Chu army, killing hundreds of people, because the battlefield was too chaotic to calculate the number of deaths for the time being, han Xin wanted to know how many troops were left, so as to make further arrangements. It was too late to directly name and count, Han Xin came up with a method of counting the arrays, first let the soldiers stand 3 people per row, and found that the last row was insufficient, and 1 person was missing to make up for the position;
Then let the soldiers stand 5 people per row, found that the last row of people is still insufficient, but also missing 1 person to fill the position; and then let the soldiers stand 7 people per row, the result is still missing 1 person to make up the phalanx. As a result, Han Xin quickly calculated the result: although the specific number of dead soldiers was not known, it was between about 400 and 500 people, and according to the phalanx calculation, the number of remaining soldiers was 1049.
This is the famous "Chinese surplus theorem", "Sun Tzu Arithmetic Classic" has many similar arithmetic title records, the classic "chicken and rabbit cage" also belongs to the same type of problem, summed up is "there are things do not know the number", but there are permutation data, according to the arranged data to calculate the number of items; song dynasty mathematician Qin Jiushao's "Nine Chapters of the Book of Numbers", Ming Dynasty mathematician Cheng Dawei's "Algorithm Tongzong" have recorded this kind of arithmetic problems, as for "Han Xin Dianbing", it is people for the purpose of figurative deduction.
Another mathematical problem is called "Han Xin walking horse to divide the oil", which is that there are two people on the side of the road who argue about dividing 10 pounds of oil, the best way is to divide it equally, but the 10 pounds of oil is full of large urns, and the tools of the two people are only an empty gourd that can hold 3 pounds of oil, and there is an empty jar that can hold 7 pounds of oil. Han Xin listened to them argue for half a day, and finally understood the reason for the matter, so he dismounted and instructed:
"Fill the gourd with oil, get 3 pounds, pour it into the jar until it is finished, and repeat it twice; so that there are 6 pounds of oil in the jar; then fill the gourd with oil and continue to pour it into the jar, this time it can fill the jar, and the gourd will have 2 pounds of oil left; then pour 6 pounds of oil from the jar into the urn, and then pour 2 pounds of oil from the gourd into the jar."
"Finally, fill the gourd, get 3 pounds of oil, pour it into the jar, and don't there be 5 pounds of oil in the jar?" One of you takes the jar and the other takes the urn, each of whom is divided into 5 pounds, and no one is more and no one is more. The two people suddenly realized that there was no such way to find tools in addition to going home! So they rejoiced and went home after dividing up the oil. Although there is an element of legend, if he can become a military expert, I think Han Xin's mathematical ability will not be bad!