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.