1, the essence of mathematics is its freedom. -Cantor

2. Mathematics has made an important contribution to observing nature. It explains the simple primitive elements in the regular structure, with which celestial bodies are built. Kepler

3. Mathematical methods permeate and dominate all theoretical branches of natural science. It has increasingly become the main symbol of measuring scientific achievements. Von Newman

Mathematicians are fascinated by nature. Without infatuation, there is no math. -Arabian Peninsula

Xiaoming is a child who likes to ask questions. One day, he became interested in the numbers 0~9: Why is it called "Arabic numerals"? So he went to ask his mother, "Since 0~9 is called" Arabic numerals ",it must have been invented by Arabs, mom?" Mom shook her head and said, "Arabic numerals were actually invented by Indians."

About 1500 years ago, Indians used a special word to represent numbers. There are 10 words, and you can write both strokes. Later, these figures were introduced into Arabia. Arabs think these numbers are simple and practical, so they are widely used in their own countries and spread to Europe.

In this way, it gradually became the number we use today. Because Arabs have played a great role in spreading these numbers, people are used to calling them' Arabic numbers'. "Xiao Ming said," so that's it. Mom, can this be called a mistake? " Mom smiled.

6. The arithmetic teacher said that there are 10 pears here ~ 6 pears have been eaten ~ how many are left? A greedy student replied, "I think we should eat the rest together."

7. Zaizai came back from school happily and asked his mother: Where is Dad? Mother saw Zaizai's excitement and asked strangely, Is Dad at home? What do you want from dad? I asked my father for fifty cents. Why? Mom asked.

Before taking the math test, my father told me that if I took 100, I would get 1 yuan, and if I took 80, I would get 80 points. "Today, I got 45 points in the math test," Zaizai replied. Mother asked in surprise: What! You only got 45 points in math? Zaizai proudly said: Yes, it takes 4 points to give up and 5 points to do math. So dad has to pay 50 cents.

8. A well-dressed girl walked into the remittance office of the post office, filled out the money order and handed it to the clerk. When the clerk saw it, he returned the bill, saying that the figures should be capitalized. The girl cocked her head and said, capitalized? How can you write a big check if it is so small?

9. The Tang Priest and his disciples are walking in the endless desert. They are hungry and tired. Pig Bajie thought: How nice it would be to have a good meal! The Monkey King is not as greedy as Bajie. Wukong just wants to drink a glass of water. The Monkey King wanted to think, a family appeared in front of him. There is only a glass of milk on the table at the door. The Monkey King hurriedly stepped forward, ready to drink.

The host family said, "Wait a minute, Great Sage. If you want to drink this glass of milk, you must answer a math problem correctly. " The Monkey King thought, just a math problem can't beat me. The Monkey King agreed. There is a problem in the host's house: pour a glass of milk, you first drink 1/2 and then drink 1/3 and finally drink all the drinks. Do you drink more milk and water? Why?

10, concepts of positive numbers and negative numbers: We call numbers like 3, 2, +0.5 and 0.03% positive numbers, which are all numbers greater than 0, and numbers like -3, -2, -0.5 and -0.03% are called negative numbers. Are all numbers less than 0. 0 is neither positive nor negative. We can use positive numbers and negative numbers to represent quantities with opposite meanings.

1 1. Concept and classification of rational numbers: integers and fractions are collectively called rational numbers. There are two main classifications of rational numbers: finite decimals and infinite cyclic decimals, which can be regarded as fractions.

12, rational number addition rule:

(1) Add two numbers with the same sign, take the same sign, and add the absolute values.

(2) When two numbers with different signs are added and the absolute values are equal, the sum is 0; When the absolute values are not equal, take the sign of the addend with the larger absolute value and subtract the smaller absolute value from the larger absolute value.

(3) When a number is added to 0, the number is still obtained.

13, rational number addition and subtraction mixed operation: according to the rational number subtraction law, all addition and subtraction operations can be unified as addition operations, and then the brackets and plus sign are omitted, and the calculation is carried out by the addition law and the addition operation law.

14. Size relation (addition and subtraction): large number-decimal = difference-difference = decimal+difference = large number.

(1) The number after the word "more" or "less" is the difference.

(2) The numbers on the left and right sides of the word "Bi" are large numbers and decimal numbers respectively.

Find the addition of large series and the subtraction of decimal or difference series.

15, the cube is square, it also has six planes, and its sides are straight. Moreover, its sides are all the same length, and each face is the same size. No matter how flat it is on the table, the height is the same, which can be used to draw a square. The Rubik's Cube is a cube.