Fourth Grade Mathematics Diary

Fourth Grade Mathematics Diary Part 1

This week, we learned about the units of area, which are square millimeters, square centimeters, square decimeters and square meters.

In the morning, after I finished writing my composition, my father asked me, "Li Ran, did you finish your homework so quickly? Let me ask you a few math questions." I said confidently: "Okay!" "One piece The area of ??the blackboard is about 400 ( )?" "The area of ??a blackboard is about 400 square decimeters. " "The area of ????that playground is about 2500 ( )?" I was dumbfounded: "square... decimeters." Dad smiled. Said: "Think about it again." I thought for a moment: a blackboard is about 400 square decimeters, and 2500 is about 6 times of 400. Ah, how can a playground be as big as 6 blackboards? "Playground The area should be 2,500 square meters." "That's right." Dad said with a smile, "Then how did you know?" "I compared it with a quick blackboard." "That's a good method. Let me ask you another question. Question, is the width of the desk 45 ( )?” “The width of the desk is 45 centimeters.”

After answering the question, my father said, “I haven’t mastered the area unit yet!” I lowered my head in shame. Fourth Grade Mathematics Diary Part 2

Today is the weekend. In the afternoon, my grandpa and grandma and I went shopping.

We walked into the "Jeanswest" store, and grandma selected three T-shirts worth 29 yuan and planned to buy them. Grandma asked me: "How much does this *** cost?" I said without thinking: "One *** is 87 yuan (29×3 is approximately equal to 90, 90-3×1=87 yuan)."

After grandma bought the clothes, we walked out of the clothing store. Grandma said: "It's half past five, let's go eat rice noodles." When we walked into the rice noodle shop, we bought a medium bowl of rice noodles, two small bowls, a steamed dumpling and two bowls of porridge. Grandma asked me: "Beibei, how much should I pay?" I said: "17 yuan per pound, because the medium portion is 4.50 yuan, the small portion is 3.50 yuan, steamed dumplings are 3.50 yuan, and rice porridge is 3.50 yuan. The portion is 1 yuan (4.53.5×3+1×2=17 yuan)”

After eating, we went home. Fourth Grade Mathematics Diary Part 3

0 is a mysterious number, which is as elusive as the mystery in the universe. 0 is also an important number. If you accidentally add one more 0 or one less 0, the consequences will be really disastrous.

There was a math test that made me truly appreciate the importance of 0. When the test paper was handed out, I scored 99 points! I immediately looked for the point of error. It turns out to be the question 450÷90. "How could I make mistakes on such a simple question?" I muttered in my mind. I remember when I was doing the oral calculation of 450÷90, I easily wrote down 50 and was very confident. But in the end, when I calculated it, it turned out to be 5, with an extra 0. This is very inappropriate! It should not be wrong, but it is wrong. Think about how important 0 is!

If I become the financial general manager of the company in the future, and someone else comes to withdraw money, it is supposed to be 1,000,000 yuan, but I miss a zero and write it as 100,000 yuan, and record 100,000 yuan on the bill. Then who should I ask for the 900,000 yuan? Fourth Grade Mathematics Diary Part 4

Winter is here, and the little squirrel needs to prepare food for the winter.

One day the little squirrel came to the forest carrying a big bag and said to Grandpa Pine Tree: Please give me your pine cones, okay? Grandpa Pine Tree was very generous and said: Do you want it? Pick as many as you like. The little squirrel was very happy. He sang while picking, and soon the bag was full. Grandpa Pine Tree asked: How many pine cones did you pick? The little squirrel said: Oops, I forgot! Grandpa Pine Tree said with a smile, "I have grown 16 pine cones, and now there are 9 more. If you can figure out how many pine cones you picked, let me know." "Carry it away." The little pine tree is anxious and doesn't know how to calculate. What should I do? If Grandpa Pine Tree doesn't let it carry it away, what will it eat in the winter? I'll help it.

In math class, the teacher said: if you know the total number, find the partial number, that is, remove a known partial number from the total number, and you will get the other partial number, and use subtraction to calculate. I quickly calculated it and the little squirrel picked 16-9=7 (pieces). Fourth Grade Mathematics Diary Part 5

Today, I had an interesting math lesson - "Move the Decimal Point to the Right".

Although the decimal point is called a "small" point, it is very difficult to jump. The decimal point of a number is moved to the right by one, two, and three places... The resulting numbers are 10 times, 100 times, and 1000 times the original number respectively...

< p> By analogy, the decimal point of a number is moved one, two, or three places to the left... The resulting numbers are one-tenth, one-hundredth, and one-thousandth of the original number respectively. ......

Please remember that although the decimal point is relatively small, he has great abilities. As long as he stretches and moves, the numbers will become larger if he wants them to. As small as possible, become smaller. Fourth Grade Mathematics Diary Part 6

Today we had an oral arithmetic acceptance check. In the second period, after Teacher Dong entered the classroom, the noisy classroom suddenly became so quiet that you could hear a pin drop.

The time is very short, I know I need to seize the time, finish the questions quickly, and then check. The students all took the time to do their oral arithmetic. As just three minutes passed, time slowly passed. Listening to Teacher Dong's "stop", the team leader quickly and quietly handed the paper to Teacher Dong.

In the afternoon, I heard Wang Zicheng say: "Yong Jiawei scored ninety-six points in the exam." I thought: "What question is wrong? Let me see quickly!" Alas! I got a few very simple questions. Wrong, I really shouldn’t. I regret it extremely. My mother usually asks me to do oral arithmetic, but I don’t do it. The consequences are very serious!

Teacher Dong informed that on December 21, the school will accept the oral arithmetic. , there are only ten days left, I have to seize the precious time, practice more oral arithmetic, get good grades, and give grandma a surprise when I get home. Fourth Grade Mathematics Diary Part 7

Wednesday, June 6, sunny

Since I was in sixth grade, I have never encountered a very difficult question in mathematics, but recently, Youdao The calculation formula makes me rack my brains!

The topic of this problem is: a pasture, the grass on the pasture grows at an average rate every day, the pasture can feed 15 cows for 20 days, and can also feed 20 cows for 10 days. So how many cows can eat the grass that grows in this pasture every day?

I have been studying for a long time, how much grass does a cow eat in a day? I don’t know how many kilograms or baskets it is, what should I do? Suddenly, I had a flash of inspiration, I have it! No matter how much I can eat, just assume it is one unit, and it will be solved easily. Assuming that the amount of grass a cow eats every day is 1, it can be calculated that the grass that 15 cows eat per day in 20 days is: 15×20×1=300, 300 is the original amount of grass in the pasture plus these 20 days New grass. You can also calculate the amount of grass that 20 cows eat for 10 days: 10×20×1=200.

However, after finding these, how to calculate it? I thought hard and finally found the way: 300-200=100. Isn’t this 100 the difference between the amount of new grass grown in 20 days and the amount of grass grown in 10 days? It means that the amount of grass grown in 10 days is 100, which is the amount of grass grown every day. The amount is: (300-200)÷(20÷10)=10.

The amount of grass a cow eats every day is 1, then the new grass that grows every day can be eaten by 10 cows for a day.

Through hard thinking, I calculated the question correctly, and my heart was as sweet as honey. My hard work finally paid off! Fourth Grade Mathematics Diary Chapter 8

We have just finished the first unit of understanding big numbers, but I am a bit confused about how big a number 100 million is. Today I plan to explore how big a number 100 million is. .

I am going to calculate how many liters there are in 100 million drops of water. I first got a syringe, sucked 2 ml of water, and dropped it drop by drop. It turns out that there are 60 drops in 2 ml of water, so there are 30 drops in 1 ml of water. I did the math again and found that 100 million drops of water actually amounted to 3333333 milliliters. In other words, the total *** is 3333 liters. One hundred million drops of water turned into 3333 liters of water, which can hold four water trucks. What a huge amount! It’s true that drops of water turned into a river. It seems that we must save every drop of water in our lives. Fourth Grade Mathematics Diary Part 9

Mathematics is a wonderful subject. It focuses more on data processing and manual practice. We can also start from this aspect when writing mathematics diaries.

Mathematics, mathematics, I love you, just like a mouse loves rice. Do you know why I like mathematics? Because mathematics is charming, I have been deeply attracted by it.

Today, I learned another new knowledge, that is - the simple algorithm of addition and subtraction. After learning the simple arithmetic of addition and subtraction, my calculation speed became much faster and it became easier to learn calculations. Give me an example! For example: 367+498=? I just think about it this way: add 498 as 500, then use 367+500, and find that 2 more are added, so I subtract 2 from the sum, and the result is 865. And what about 796+295? I think about it this way: 796 can be added as 800, and 29 can be added as 300. One adds 4 more, and the other adds 5 more, so the calculation becomes 80300-4-5=1091 , look, how convenient it is!

After learning the simple algorithm for addition, it will be much easier to learn the simple algorithm for subtraction. Such as: 483-299, hehe, I just moved my head and there is a method. I first subtracted 299 as 300, because 1 was subtracted, so as long as 1 is added to the result, 483-301=184 is used, which is much easier. However, I can warn you: when calculating subtraction, it is best not to think about the minuend, otherwise it will be troublesome!

Now, I like mathematics more and more, because it allows me to learn quickly The calculation results, mathematics really makes me have endless aftertaste!