Last night, my grandmother and I went to buy watermelons. This time, my task is to bargain with melon farmers and buy delicious watermelons. There is a row of stalls selling melons at the entrance of the community. I came to the first melon stall first, because it was my first time to buy watermelon independently. I asked her gently, "How much is the watermelon?" "Seven cents." I thought to myself: Why is watermelon so cheap? ! I said, "1 yuan can I buy two?" The melon farmer smiled and said, "Five or six dollars each. Do you want to buy two for a dollar? Seventy cents a catty. " "Oh." I feel particularly embarrassed. I suddenly found a melon stall selling yellow watermelons, which is my favorite. "Haha, this will help me out!" I immediately pulled my grandmother: "Grandma, let's buy yellow watermelons." Then I ran away as fast as I could.

This time, I have some experience and know what the melon farmers mean by 70 cents! I want to bargain with him at once. But grandma said I couldn't do it, so she bought two watermelons, but they were only fifty cents cheaper, that is, sixty-five catties.

After I sent the watermelon home, I was still unwilling and went to another melon stall myself. I successfully negotiated the price this time, and my performance was much better than grandma's: in the past, it was 70 cents a catty, but I cut it to 65 cents a catty and picked a watermelon, weighing 9 kilograms, which is 9x0. 65=5。 85 yuan, I had five smooth talks. 5 yuan, deal.

Buying melons this time is not a small gain!

Excellent Diary of Mathematics in Grade 24: 400 words.

Today, I finished my homework early in the morning. My mother saw it and came up to me and said, "Zini, play a game with you!" " ""good! " I readily agreed. Mother brought a round cardboard and fixed a rotatable pointer in the center of the cardboard with a nail. The cardboard is divided into 24 grids on average, and the number 1-24 is written in each grid. "Mom, what are the rules of the game? Say it! "I said impatiently that the rules of the game are simple, that is, when the pointer turns to an odd or even cell, the next number must be added. If it adds up to an odd number, I win; If the total is even, you win. "Mom said with a smile.

I saw that the rules of the game were very simple. I played for more than a dozen times in a row, but I couldn't beat my mother every time. My mother smiled. "Why is it always singular?" I asked my mother puzzled. Mom said, "Think for yourself!" So, I racked my brains to think, and finally reminded me of the formula that the teacher once said: odd+even = odd. Now I can see that if the pointer points to the odd number, then the next number must be even; If the pointer points to an even grid, then the next number added is odd, so no matter where the pointer points, the number added is odd. Mom won with this rule.

In the world of mathematics, there are many wonderful laws. As long as we learn math well and make good use of it, it is everywhere!

Excellent math diary with 400 words in the third and fourth grades.

Today, my father gave me a task to estimate the number of people in Chen Kai community. How can I finish this task? You can't let me count them one by one, can you? I've been thinking about it for a long time. If I could know how many houses there are in Chen Kai community, how many families there are in each house and how many people there are in each family, I would come out!

How do I know how many houses there are in Chen Kai community? As I remember, there was a map showing the distribution of communities in Chen Kai. I'll go downstairs and find the distribution map right away. I saw that the house number on the map was 16 1. But not all 16 1 buildings are the same height. There are villas, small high-rise buildings and multi-storey apartments. There are three small high-rise buildings, 1 1 floor, each with two house numbers; There are 10 villas with 1 house numbers respectively. The rest are all six-story multi-storey apartments. How many house numbers are there in a multi-storey apartment? It should be calculated as follows:161; ; 3×2; ; 10× 1= 145。

Knowing the number and floor of the house, I can calculate the number of households, but how many people should each household count? I assume that there are three people in each household. Total number of villas = 10× 3 = 30 people; The total number of people in small and high floors = 3× 2×11× 2× 3 = 396; Total number of multi-storey apartments: 145× 6× 2× 3 = 5220. So the total number of people in the community is 30+396+5220 = 5646.

I feel very happy after finishing my father's task. I feel quite capable, and it is not easy to count the people living in the community.

Excellent Diary of Mathematics in Grade Four, 400 words.

I was doing the seventh week math exercise paper this morning, hehe, interesting. Before writing, I showed my grandfather the time. The teacher stipulated that it should be finished within 70 minutes. Can I do that?

I have calculated it, but there is a conceptual problem that makes me hesitate: the cover of the math textbook is about 54 (), and the appropriate unit name should be filled in brackets. It must be too small to fill in "square centimeter", so I filled in "square decimeter" immediately. However, is the cover of the book this big? Grandpa is wrong to think about it. There is no such a huge math textbook. What should I do? I said, "Let's wait until the teacher approves it on Monday." Grandpa drew a point between 5 and 4 with a pen, and it became "5.4 square decimeter", but I still said, "Let's wait until the teacher approves it on Monday."

One more question: a rope is folded in half four times. How much is this rope per short section? As soon as I got the rope, I folded it in half. Grandpa said, "Folding once is half, twice is a quarter, and three times?" What about four times? "I suddenly understood, I blurted out," three times is one eighth, and four times is one sixteenth. "There is another problem: there are six pieces left in a box of cakes, which is three quarters of the original. How many pieces are there in this box of cakes?

I was confused at first, but then I thought about it and did it. Thinking about your little head is still not smart enough! But this paper was written in 60 minutes.

Excellent Diary of Mathematics in Grade 5 and 4, 400 words.

Everyone is talking about saving water, but how many people have done it? Today, I did an experiment: I put the bowl under a dripping faucet. In one minute, I counted 28 drops of water in the tap. I think: if I save 28 drops per minute, how many drops can I save in an hour according to this calculation? How was your day? 28× 60 = 1680 (drops), 1680× 24 = 40320 (drops). If every month is calculated as 30 days, every year is calculated as 12 months, one ton of water is about 20 million drops. That is, 40320× 30 = 1209600 (drops),1209600×12 =14515200 (drops), which is nearly one ton. Wow, you can save so much water in a year!

I was shocked to see such a large number. If every household saves so many drops of water every day, the water consumption will be reduced and the water fee will be reduced. Isn't this the best of both worlds? However, if every household wastes so many drops of water every day, can Grandpa Earth persist?

Water is not inexhaustible. In our daily life, because some units and individuals lack water crisis awareness and water-saving awareness, water resources waste can be seen everywhere. It is really deplorable to watch the "rushing" loss of water resources.

Let's talk about saving water. There are many ways to save water, such as washing vegetables with rice washing water, watering flowers with fish tanks, flushing toilets with bath water ... and washing vegetables with rice washing water can effectively remove pesticide residues on vegetables.

Implementing water conservation in families can save 70% of water as long as we get rid of bad habits. There are many examples of family wasting water, such as washing away odds and ends with toilet water, wasting a lot of cold water for a cup of hot water, and failing to maintain the equipment in time when it leaks.

Excellent math diary with 400 words in June 4th grade.

There is mathematics everywhere in life, which plays an important role in life. Mathematics is needed everywhere in life because it can solve many problems in life. My sister used it on her birthday. At noon on Sunday, my sister celebrated her tenth birthday and came to the hotel. I saw a lot of people. She invited six classmates, one sister and one brother, plus me and ten people. Ten of us were alone in a private room, and the cake came. My sister doesn't know how to divide it fairly, because she is worried that if there are too many people and too few people, everyone will be angry. At this time, I proposed: "We divide this cake into ten parts on average, and each person's cake share accounts for one tenth of the total cake, which is only fair."

"Yes, but what if one tenth of each person is not enough to eat?"

"Then use another method. Everyone cuts as much as possible according to their own appetite, so that no one will have any objection."

In this way, we shared the cake. We ate the cake and were very happy. The birthday party soon ended and everyone went home happily.

Birthday parties let me know how important math is. Only by learning math well can I show myself in front of others.