2 Math Diaries Be a little longer

Recently, we have learned about the re-recognition of fractions, and the re-recognition of fractions is no longer just a fraction. Instead, a graph is used to represent the fraction, for example, a circle, divided into four equal pieces, each of which is a quarter of the circle. We also learned about true and false fractions.

A false fraction is one in which the denominator is smaller than the numerator or the same as the numerator, while a true fraction is one in which the denominator is larger than the numerator. So the false fraction is greater than 1, and the true fraction is less than 1.

For example, if there are two identical figures, each figure is divided into two equal parts, the first figure is painted with two squares (one-half), and the second figure is painted with only one square (one-half). These two graphs can be described as true fractions, which are only one in four, and three in two when described as false fractions. It can also be described as one and a half.

This is a band fraction, which is a combination of an integer and a true fraction.

False fractions can be turned into band fractions, and band scores can be turned into false scores. How do fake fractions become banded fractions? Divide its numerator by its denominator, and then read it from top to bottom.

For example, if it is seven-thirds, it will be two and a third. The quotient is the integer, the divisor is the denominator, and the remainder is the numerator. So it's two and a third.

We also learned about fractions and division, where dividing a dividend by a divisor is equal to a dividend fraction of a divisor.

Last week, we studied fractions. Fractions have numerators, denominators and fraction lines, for example: 1 3, 3 is the denominator, 1 is the numerator, and the middle horizontal is the fraction line.

There are many places where you need to use fractions in your life, for example: a book has 30 pages, and each page is 1 30 of a book. Fractions can also be used to add or subtract!

For example, one half plus one half equals two in half, which is 1. Why is this so?

If a loaf of bread divides it into two equal parts, each of which is 1 2 of the loaf, and then the two portions are put together, and there are 2 1 2, which is exactly one loaf. When adding and subtracting fractions, if the denominator is the same, ignore the denominator and add the numerators. And the numerator and denominator of 2 2 are the same, which is 1.

I also learned to compare the size of the fraction, and the teacher taught us the formula: the numerator is the same as the denominator, the fraction with the larger denominator is smaller, and the fraction with the smaller denominator is larger; The denominator is the same as the fraction larger than the numerator, and the fraction with the smaller numerator is smaller.

The teacher also reminded us that when writing fractions, we generally write the score line first, which means the average score, then the denominator, and finally the numerator.

Today, when I came home from school, I suddenly saw a lot of people gathered in front of a store. I took a closer look, it turned out that the store was carrying out ** activities, as long as you pay one yuan to answer a question, if you can answer correctly within 30 seconds, you can get a prize of 30 yuan. When I saw the others being defeated, I thought:

What is so difficult? With curiosity, he paid a dollar.

I followed the boss into the store, and he began to ask: "Xiao Ming went to the bookstore to buy books, and bought 17 books for 99 yuan, how much did he spend in total?" As soon as he finished speaking, he gave a sly look and began to count the time.

Time passed second by second, and my sweat flowed down drop by drop, how can this 99 times 17 be calculated without vertical calculation? At this moment, I had a flash of inspiration, and there was a page in "Oral Calculation Quick Calculation Daily Practice" that did not say this: A quick calculation method of multiplying a number within 100 by 99 is:

Multiply this number by 100 and subtract it. Thinking of this, I blurted out, "1683."

As soon as I finished speaking, the boss almost fell to the ground, and when he looked at the timer, it was only 28 seconds, and he gave me the money helplessly.

I walked out of the store with 30 yuan in my hand, looking at the envious eyes of others, not to mention how happy I was. At this time, I thought: mathematics is not just a calculation of 1 1, it is also very useful in life, in addition to this thing, mathematics can be used in shopping and other things.

So, again, I wanted to say, "Math, it's really useful." ”

l"〈"Bu, instrumental analysis. State-state.

April Day - Good night for my baby wife? So I want to die、So I'll be more competitive ranking the next morning to wake up and sit because there is no schedule! I can't tolerate myself and have the ability to make your living expenses and education cost a lot of trouble and take care of the children.,There's me in your place.、A person who has been persevering at home to sleep is it.、So delicious??

It won't be really good, whether these can be used until the heavens are old.

Today, I happened to see you in a book.

To such an incredible data: "One.

The thickness of the paper with a thickness of centimeters is even higher than that of Mount Everest after 30 folds? ”

No matter how you listen to this data, I think it's a little too "ridiculous". After all, it is a thin piece of paper, can it really surpass Mount Everest by folding? But a lot of unexpected things can happen, so it is only through calculations that the mystery of all this can be revealed.

Immediately, I multiplied the centimeter by 2 consecutively, for a total of 30 times, to get the centimeter. Then, I converted the height of Mount Everest into 884813 centimeters, and by comparison, it was clear that the thickness of the paper after 30 folds was indeed better than the height of Mount Everest, and it was more than 10 times that of the latter.

In fact, amazing data like this is everywhere in ordinary life, as long as you have a pair of eyes that are good at discovery.

Today at noon, I was doing my math summer homework. Writing and writing, unfortunately encountered a difficult question, I thought about it for a long time and didn't come up with a reason, this question is like this:

There is a cuboid with the product of the two areas on the front and above being 209 square centimeters, and the length, width, and height are all prime numbers. Find its volume.

When I saw it, I thought, "That's a really hard question!" Only the product of the two surface areas is known, and the volume must also know the length, width, and height, and it doesn't hint at all. How do you get started?

Just as I was scratching my ears and cheeks in a hurry, a colleague of my mom came. He first taught me to use equations to solve, but I was not very familiar with this method. So, he taught me another way:

List the numbers first, then exclude them one by one. We first listed a number of numbers according to the requirements of the question, such as prime numbers such as , and then we started to exclude, and then we found that there were only two numbers left, 11 and 19.

The sum of the edges (and the lengths are prime). So, I began to tell which of the two numbers was which.

In the end, I got the result, which was 374 cubic centimeters. My equation is: 209 11 19

11 2 17 374 (cubic centimeters).

Later, I used what I learned this semester: decomposing prime factors to solve this problem, and the result was exactly the same.

After solving this problem, I was happier than anyone else. I've also learned that mathematics is full of mysteries waiting to be discovered.

1.Today, our family went to KFC to eat the whole family**.

When we got there, there was a crowd of people, and we finally ordered a good meal and found a seat to sit down. The dish is here, it's a big bucket **. There are 12 chicken thighs in it, I think:

How do you average the score? At this point, I remembered the division 12 3=4. We each had four chicken legs, and I later ate 1 chicken leg from my mother and 2 chicken legs from my aunt, and my aunt said:

You can't eat it for nothing, I ask you, how many fractions of a meal have you eaten? How many more servings do you eat and eat them all? "I thought about it,:

I ate 7 12, then 5 12 and I ate it all. "Luckily, I learned about fractions and was able to get the questions right.

2.Today, my mother gave me 10 yuan to go to the supermarket to buy something. I bought a string of firecrackers for 2 10, bought four lollipops for 1 10, bought 7 balloons, used 2 10, and finally bought a comb, used 4 10 for money, and made a total of 2 10 + 1 10 + 2 10 + 4 10 = 9 10.

I had to pay my mother back with one dollar left.