Mathematical knowledge is like a chain, which is linked one by one. As long as you study hard, you will find that a lot of knowledge can be solved with what we have learned, and you will find that our math learning becomes easier and more interesting.

Article 1: math diary Forest is an excellent fourth grade once a year? Math contest? . Here we go. The bird said: Listen, any number in the world is the sum and multiplication of all numbers. What is the product? It's quiet down there.

? Equal to 0? . The chicken cried, and the red team scored ten points.

The bird said again:? 2+21+211= 7, let this formula hold? .

The clever fox said? 2+2+2+ 1=7, this formula holds? . The blue team scored ten points. The following thunderous applause.

The bird said, there are seven pockets, and the money in them is less than 20. What's the minimum? How much is it at most?

As soon as the words were finished, the puppy said, at least take 28 yuan, and at most 1 12 yuan? .

? Wow! What a genius! Blue team plus 20 points? .

? 1+2+3+4+5+6+7+8+9=35, just change the number to make the formula hold? .

Sons of liberty said? Just change +5 to -5, one plus one MINUS, isn't it 10? . Red team plus 10 points.

This is the last question, worth 30 points. Listen carefully. In the English competition, Class One is not the first, Class Three is not the last, Class Four is the third, and Class Two is in front of Class Three. Do you know the ranking order?

The kitten is whispering: I see, class two is the first, class three is the second, class four is the third and class one is the fourth. ? The blue team scored 30 points.

The bird said that the red team won the math contest, and the blue team won the red team 60-20. ?

The second chapter: The annual math contest of math diary, an excellent fourth grade, has begun. The forest is very lively. This year's contestants are: cotton seed, turtle, tiger and lion.

The game has already started. Teacher Swan first gave each of these candidates a test paper, and then said to them: whoever can calculate correctly and quickly in a certain period of time will win the Wisdom Cup Award. ?

As soon as Mr. Swan finished. These candidates began to write. Rabbits run fast and do fast. I saw that she was very clever and soon finished more than half of it. Come on, let's have a look at its test paper. ? Dizzy! ! ! ? You see: 80-70 =150,20? 4=80. How careless! I didn't even see the operation symbols clearly.

Look at the lion and the tiger. Hey! Why don't you see lions and tigers? I only saw a lot of manuscripts. Before I left, I saw lions and tigers busy! It turns out that every time a lion does something, he has to take out the manuscript paper to calculate. The more manuscripts are piled up, the more lion heads are hidden. Really simple-minded, developed limbs. Tigers are more exaggerated. Every time I finish a question, I will take out my manuscript and check it. No wonder you are sweating.

Finally, let's look at the tortoise!

The tortoise is usually slow-tempered, but this time its thinking is not slow at all. See how wonderful this question is: 3456-999 = 3456-1000+1= 2457. The tortoise uses a simple algorithm to finish the test paper quickly, and it is right and fast!

Finally, the tortoise won the wisdom prize.

Chapter III: math diary, an outstanding fourth-grade student, learned the method of overall planning in math class today, and also understood the value of time more. It is the most reasonable method to arrange time by overall planning, which will greatly reduce unnecessary time consumption. In life, there are many things that can be taken as a whole.

For example, I cook a fruit dinner for my parents. Prepare for 5 minutes, soak the fruit for 5 minutes, cut the fruit for 7 minutes, decorate for 2 minutes, and cool the juice 10 minute. Arrange the time with the overall planning method, get ready when soaking the fruit, * * * 5 minutes, and then take a bottle of juice to remove the ice. In this process, you can also cut the fruit and set the fruit. It only took 9 minutes, and there is still 1 minute to rest. It is indicated by the flow chart: soaking the fruit (preparing at the same time) and freezing the juice (cutting and discharging the fruit at the same time) * * * takes 15 minutes. What a time saver.

Another example: get up in the morning for 5 minutes, make the bed for 5 minutes, wash for 5 minutes, warm milk 10 minutes. Then you can warm the milk after getting up. In this process, you can wash your face and make your bed, so you can drink milk in 10 minutes, which is very time-saving.

Time is money. Time is precious, once lost, it will never come back. If we do everything in a coordinated way, we will use our time very tightly and won't let it go to waste!

Chapter Four: Excellent math diary in Grade Four. Today is Sunday. When I do my math homework, will you do it? Try your hand? I saw two calculation problems, namely: 3? 999+3+8? 99+8+ 10? 99+ 10+2? 9999+2=? And 333? 334+222? 999=? . I've been doing it for a while, but I still can't. I quickly asked my mother to teach me. My mother came to have a look and said that these two questions can be applied to the multiplication algorithm you have learned. What multiplication algorithms have you learned? I replied: multiplicative commutative law, multiplicative associative law, multiplicative distribution rate. ? Mother nodded with satisfaction and patiently explained to me.

Mom said:? 3? 999+3=3? 999+3? 1=3? (999+ 1)=3? 1000=3000, and the multiplication distribution rate is used here. Do the math yourself. I thought about it and said excitedly, I do! I will! 8? 99+8=8? 99+8? 1=8? (99+ 1)=8? 100=800; 10? 99+ 10= 10? 99+ 10? 1= 10? (99+ 1)= 10? 100= 1000; 2? 9999+2=2? 9999+2? 1=2? (9999+ 1)=2? 10000=20000; Finally, add up to get the final number, that is, 3000+800+1000+20000 = 24800. ? Mother nodded with satisfaction and said, not bad, my son is really high! ?

The second question was prompted by my mother. She said: 999=333? 3. Think about what you should do. I still don't know how to do it. Mom said again: Actually, 333? 334+222? 999=333? 334+222? 333? 3=333? 334+333? (222? 3)=333? 334+333? 666? Then I suddenly realized that it was like this, so I went on to say: equal to 333? (334+666)=333? 1000=333000? . I thought it was funny, so I burst out laughing.

Mom then asked:? What multiplication laws are used in these two questions? I replied: there are multiplicative associative laws, multiplicative commutative laws and multiplicative distribution rates. In short, all the multiplication algorithms are used. ? Through my mother's explanation, I learned more knowledge, and complex calculation problems can be simplified by algorithms.

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