In life, mathematics is everywhere. For example: buy food! Buy stationery! Measuring cloth, etc. , all need to use mathematics.

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 oranges together. A kilo of oranges 1.8 yuan. My mother bought 4.5 kg and should pay 8. 1 yuan. But the clerk was careless and didn't know how to calculate it, so it became 9 yuan money. 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 how to multiply and divide decimals in such a small city, but my mother also praised me for saving her 0.9 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 0.9 yuan that will lose, but also hundreds, thousands or even hundreds of millions!

Chapter two: the first volume of grade five, math diary.

My sister and I are having a good time, and my grandmother insists on calling me and asking me to settle her account.

Grandma bought 3 Jin 4 Liang eggs, 3 yuan and 50 cents per Jin. Grandma handed it in 12 yuan. How much should I get back? As soon as grandma's voice fell, grandpa said, "Change 1 minute!" I don't believe that grandpa can calculate so fast, so I use the mathematical knowledge I have learned to calculate: unit price multiplied by quantity = total price; Spent money = recovered money, exactly the same as grandpa's, and the change is 1 minute. I asked grandpa why he calculated so fast. It turned out that Grandpa divided the five corners of 3 yuan into 3 yuan+five corners, first 3.4 times 3= 10.2 yuan, then 3.4 times 0.5, and half of 3.4 is 17 yuan, so a * * spent119 yuan and paid1. After grandpa finished, I realized that he used multiplication and division.

Through this incident, I understand that mathematics can be used anywhere around us. Let mathematics serve us!

Chapter Three: math diary, Grade Five, Book One.

Take 10 to buy books on the third floor of Trust-Mart today.

I searched and found a book "Myths and Legends". When I saw the cover, I knew there were many wonderful stories in it. I decided to buy it, but when I saw the price, I was shocked again. It turns out that this book is 1 1 yuan. Feel the money in my pocket when reading this book. I'm really embarrassed!

The assistant aunt saw my embarrassment and asked kindly, "What's the matter, little friend?" I said shyly, "I want to buy this book, but I don't have enough money." She asked again, "How much money did you bring?" "Cai 10 yuan." I said. Aunt smiled and said, "Look at the price tag, little friend. It also says' Book sales are discounted, all of them are 10% off'." I asked, "What do you mean by' 10% discount'?" Aunt said: "It is to collect money at nine tenths of the pricing. For example, 10 yuan's books only accept 9 yuan."

I calculated that this book is only 9.90 yuan. "Yes!" I thank my aunt again and again.

I bought a satisfactory book today and learned knowledge. I'm so happy!