Math diary, volume 2, grade 4 1
It's sunny on Sunday, September 16.
The number χ is very special. It looks like an "X".
One day, several digital friends such as "1", "2", "3" and "4" got together to compare the sizes.
Suddenly "χ" appeared in front of them and said, "Stop competing! You are no match for me! " 1 said, "How can you compare with us? You don't even know what you are, and you dare to come here and compete with us. Hey, what a young man! "
Not convinced, χ jumped in front of χ 1 and said loudly, χ- 1=9, χ=9+ 1, χ= 10. Look, I am older than 9! "
As soon as it heard "0" in the cave, it rolled out, pulled the number "1" and ran to "χ" and said, "χ× 1=0, χ=0, which is smaller than anyone else."
After hearing "0", "χ" is no longer proud.
Math diary II, Volume II, Grade Four
It will be sunny on Sunday, September 29th.
Life is inseparable from electricity, and our family has to pay the electricity bill every month. According to my mother, the electricity consumption per kilowatt hour is 0.69 yuan, and our family consumes about 6 kilowatt hours every day, so 0.69×6=4. 14 yuan, and our family consumes 4. 14 yuan every day. Returning home during the Spring Festival 1 1 day, the electricity saved is:11× 0.69× 4.14 = 31.41yuan.
Wow! Go home 1 1 day and save 3 1.42 yuan electricity bill. Our monthly electricity bill is 4.4 1×30= 124.2 yuan. The annual cost is124.2×12 =1490.4 yuan. Wow! Our electricity bill is more than 1000 yuan a year, so we have to save electricity.
The fourth grade, the second volume, math diary, Chapter III
September 2 1 Sunday sunny
This semester, the teacher taught a new knowledge, that is, the multiplication and division of decimals. This knowledge helps me a lot!
Last night, my mother went to buy apples together. A kilo of apples is from 2.6 yuan, and my mother bought 4.5 kilos. I should pay 9 yuan. But the clerk is careless and doesn't know how to calculate. Yes 12.2 yuan. Fortunately, this semester, I used the knowledge of Protestantism, and after doing a calculation in my mind, I immediately corrected the salesman's mistake.
Not only did my aunt, the shop assistant, praise me for my cleverness and my ability to multiply and divide decimals in such a small city, but my mother also praised me for saving her 0.5 yuan on the way home, and the knowledge I learned can be applied in my life. Yes! If you don't learn this math well, it's not only 0.5 yuan that will lose, but also hundreds, thousands or even hundreds of millions!