Today, I followed my mother to the market to buy food. Mom said, "I will test you today. Will you buy a dish you like?" My mother gave me 20 yuan to watch my performance. "Make sure the task is completed." I said confidently. So, I walked and watched, and came to the vegetable area. At this moment, I saw an aunt selling white and tender fresh mushrooms. I think: the leftovers at home can be cooked with mushrooms. So, I asked the aunt who sells vegetables: "Aunt, how much is a catty of mushrooms?" Aunt smiled and said to me, "Little friend, this mushroom costs 7 yuan a catty. How much catty do you want?" "Aunt, I only need to buy half a catty." I think: 7 divided by 2 equals 3.5 yuan, 20 minus 3.5 equals 16.5 yuan. After thinking about it, I gave my aunt a note of money from 20 yuan, reminding her that she still needs to find me 16.5 yuan. I went to the meat department again and saw an uncle selling meat, so I asked, "Uncle, how much is a catty of meat?" "10 yuan a catty." "Then I'll buy a catty." I thought: 16.5 minus 10 equals 6.5 yuan. I handed the 10 yuan in 6.5 yuan to my uncle.

When I came out of the food market, my mother smiled and said to me, "Learn to buy food!" " When she saw that I had both meat and vegetables and 6.5 yuan in my hand.

Through this test, I feel that there are many mysteries of mathematics hidden in our lives, and the ability to learn mathematics is really important. And don't be proud. You should study hard and master more math skills in order to apply what you have learned and solve the problems around you.

: math diary 400 words

I saw a topic "Mathematics in Life" in my math textbook today. The topic is: "China's population is about 654.38+0.3 billion. If we save 654.38+0 cents per person per day, if so, our country will save about 6.5438+0.3 million yuan. If primary school students need to save about 65438+ tens of thousands of dollars from grade one to college, then this money can be provided to 1805 children who are out of school and have no money to go to school. Wouldn't it be nice to give these money to those people? "

After reading the above information, I thought: many hands make light work. Suddenly I remembered, many hands make light work? Not good, because I thought about it: if this population of about 65.438+300 million wastes 65.438+0 drops of water, then a * * wastes about 65.438+300 million drops of water, then what do you think is 65.438+300 million drops of water?

I did a small experiment: I put 1000 drops of water under the tap and weighed them with a scale. The weight of 1000 drops is 200 grams. I wrote another calculation.

130000000÷1000× 200 = 260000000 (g)

260000000 grams =260 tons

I really don't know, it's shocking: if everyone uses one ton of water a month, then 260 tons of water can be used for two years. I went to ask my father, "How many kilowatt hours can a ton of water generate?" Dad said, "1 ton of water can generate 100 kwh of electricity." This means that 260 tons of water can generate 26,000 degrees of electricity.

Wow! I was shocked at once. 260 tons of water can play so many roles! So we should save all the water now, don't waste a drop of water, we should form a good habit of saving, and we can't waste any more.