Arabic numerals were invented by ancient Indians and later spread to Arabia and Europe. Europeans mistakenly thought it was invented by Arabs, so they called it "Arabic numerals". Because it has been circulated for many years, people call it Yi, so people still mistakenly believe that these numerical symbols invented by ancient Indians are called Arabic numerals.

multiplication table

Jiujiuge is the multiplication formula we use now. As early as the Spring and Autumn Period and the Warring States Period BC, Jiujiu songs have been widely used by people. In many works at that time, there were records about Jiujiu songs. The original 99 songs started from "99.8 1" to "22.24", with 36 sentences. Because it started with "998 1", it was named 99 Song.

The expansion of Jiujiu Song to "One for One" was between the 5th century and10th century. It was in the 13 and 14 centuries that the order of Jiujiu songs became the same as it is now, from "one for one" to "9981". At present, there are two kinds of multiplication formulas used in China. One is a 45-sentence formula, usually called "Xiao Jiujiu"; There is also a sentence 8 1, which is usually called "Big Uncle Nine".

Third, Mobius ring

Mobius ring is a topological structure with only one face and one boundary. You can twist a piece of paper into 180 degrees, and then stick the two ends together to form a Mobius ring.

A short story of a mathematical scientist

Gauss was interested in mathematics when he was in elementary school. One day, Mr. Baxter, the math teacher, was a little unhappy. As soon as he entered the classroom, he said to his classmates with a straight face, "Today's class is calculated by yourself. Whoever finishes the calculation first will go home for dinner first. " With that, he wrote such a topic on the blackboard:

1+2+3+……+ 100=?

The students immediately took out their exercise books and bowed their heads and calculated carefully. Burt sat reading a novel. Who knows, he just finished reading a page when little Gauss raised his hand and reported to the teacher:

"Teacher, I have finished this problem."

"finished?" Bert waved angrily. "You must be so quick. Do it again! "

"Can't be wrong. I checked and checked. " Gauss said confidently. "Bert went to Gauss's seat and picked up his exercise book. The answer is "5050", which is obviously true.

"How do you calculate?" Bert asked in some surprise.

Gauss answered matter-of-factly: "I found that the sum of the two numbers in this question is 10 1, and the total is * * * 5010/,so the answer should be: 50×1= 5050."

"Great!" Baxter patted the table excitedly, and then loudly said to all the students, "I didn't expect that there would be a math prodigy among you!" " "

Since then, Mr Burt has completely changed his views on rural children, especially Gauss. Later, under the careful training of Mr. Bertrand, Gauss became more and more interested in mathematics and gained more and more accomplishments. /kloc-at the age of 0/7, he discovered the quadratic reciprocity law in number theory.