Simple operation is at hand.
Mathematics is indeed everywhere in our daily life.
On Saturday night, my mother took me to Haibei discount store to buy clothes. The clothes there are 20% off. Mom bought a coat with an original price of 458 yuan and a pair of pants with a marked price of 128 yuan. The shopkeeper adds up the original price of the coat and trousers, and then gives a 20% discount. The formula is: (yuan). I read it and thought, "If we each give a 20% discount first, and then add it up, will it be cheaper?"
When I got home, I listed the following formula on the paper: "458 ╳ 0.8+128 ╳ 0.8 = 366.4+104.4 = 468.8 (yuan). To my surprise, how can the result be the same? I compared the shopkeeper's formula with mine and found that this is not the application of multiplication and division in mathematics.
It seems that mathematics is in life.
Problems caused by fuel tax
My family has a Jetta car, and the annual road maintenance fee, insurance fee, oil fee and maintenance fee total more than 10,000.
This year, a fuel tax per liter of 0.8 yuan will be levied, and road maintenance fees will be exempted. Is the fare in our family more expensive or cheaper than before?
Our car is mainly used by my father for work. Travel about 30 kilometers a day, 22 days a month, 660 kilometers, and 7920 kilometers a year, which is about 8000 kilometers.
Our Jetta car uses about 8 liters of oil per 100 km, and the oil consumption in that year is about (8000÷ 100)×8=640 liters. * * * Pay fuel tax 0.8×640=5 12 (Yuan). Less than the annual road maintenance fee 1440 yuan 1440-5 12 = 928 yuan. Therefore, it is cost-effective for our family to levy fuel tax and exempt from road maintenance fees.
How many kilometers do you drive every day, and will the cost be the same as before? I thought of a backward method.
1How many liters of fuel is the road maintenance fee in 440 yuan? 1440 0.8 = 1800 (length)
How far can this oil go? 1800÷8× 100=22500 km
Average monthly driving time is 22,500 ÷12 =1875 (km).
Average daily driving 1875÷22≈85 (km).
Therefore, if our car travels about 85 kilometers every day, the cost is roughly the same as that before fuel tax; If you drive more than 85 kilometers a day on average, you will spend more than before. Now our car travels about 30 kilometers a day on average, which is much more cost-effective than before.
Clever calculation result
A few weeks ago, our class had a Chinese exam. After handing out the papers, Teacher Yang asked us to grade them ourselves.
When I read the test paper, I scored 0.5 in the front, 1.5 in the back and 3 in the back, 1.5 in the back. I am very happy because I have surpassed the study committee of our class.
Suddenly my deskmate asked me to help him grade. Let me see: -7.5, -4.5, -0.5, -8, -5.5,-1 1.5,-10, damn it! With so many deductions, it's no wonder that he didn't figure it out after five calculations.
I began to calculate. First add 4.5 and 5.5 to get the integer 10. 8, 1 1.5 and 0.5 are added to get the integer 20; Then add 10, 20, 10 and 7.5 to get 47.5; Finally, use 100-47.5=52.5 (point).
I worked out the score easily. Have you learned this simple method?
Precious water
Today, Mr. X, a math teacher, told me something. One morning, her husband wanted to wash clothes for the children. When the tap was turned on, he found it was frozen. I forgot to turn off the tap because I was in a hurry to go to work. When I got home at night, I found the sound of running water in the bathroom. Teacher X asked me, "Can you help me calculate how much water my family wasted today?
When I heard this, I froze. No conditions, how to answer? I went to ask my father, "Dad, when will the frozen water thaw in the morning?" "Around 8 o'clock." Dad replied.
I thought, "As long as you know the water flow in one minute, you can calculate the water flow of 1 hour, and finally calculate the total running time of the faucet. Isn't this problem solved?"
As soon as I got up, I turned on the tap, took out a 600 ml beverage bottle to get water, and counted 1, 2, 3, 4, 5 in my mind. It's full.
I thought, "If 600 ml of water flows in 5 seconds, then 1 min, 600╳(60÷5)=7200 ml." . Then 1 hour will flow 7200╳60=432000 (ml), or 432 liters. How long has the tap been on? I was lost in thought again.
"That's right!" I am ecstatic. "The teacher works very hard. It is estimated that she will have to go home at 6 o'clock. Is this not good? " I thought about it, and then I figured it out: "From 8: 00 to 18: 00, a * * * is 10 hour. Then a faucet * * * flows 432╳ 10=4320 liters or 4.32 cubic meters. At present, the water fee per ton is 2.5 yuan, and 4.32 cubic meters (4.32 tons) of water is 4.32╳2.5= 1 1.8 yuan.
Teacher X wasted 10.8 yuan water fee.
Although the water fee of 1 1 yuan is not particularly large, how much water resources will be wasted if everyone does this! China has a population of 654.38+03 billion, and each person wastes 65.438+065.438+0 yuan, which is 654.38+043 billion yuan. What a huge amount of data this is. Therefore, we must cherish water resources and never let our tears become the last drop of water in the world.