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连乘乘加乘减的教案连乘乘加乘减的教案连乘乘加乘减的教案1教学内容：教科书第9页的例６及做一做，练习三第1～4题教学目的：知道整数乘法的交换律、结合律、分配律，对于小数乘法同样适用；掌握小数连乘、乘加、乘减的计算方法；培养学生的迁移和类推能力；养成认真细心的良好习惯。
教学重点：正确计算小数连乘、乘加、乘减教学难点：理解整数乘法的运算定律在小数乘法中同样适用教学过程：一、复习导入１、出示：先想一想下面各题的运算顺序，再计算12×5×6030×7＋__×4－问：①每个式题各含什么运算？是什么式题？②每题的运算顺序是怎样的？③指名口答２、引入新课：小数的运算顺序同整数一样板书课题：小数连乘乘加乘减二、进行新课(一)教学例６１、出示例６(1)读题(2)列出算式(3)问：算式中有几步计算？是什么式题？每个数目都是小数吗？(4)这个含有小数的连乘式题应该先算什么？(5)运算２、练习Ｐ９做一做(1)先指名说说运算顺序，再计算(2)指名板演集体订正(二)教学整数乘法运算定律推广到小数乘法１、准备题下面简算中用到了哪些运算定律？7×12＝12×78×5×4＝8×(5×4)(24＋36)×5＝24×5＋36×5指名口述各定律内容问：这些乘法运算定律中交换律中两个数的范围是什么？结合律中三个数的范围是什么？分配律中的三个数的范围是什么？２、过渡：那么小数乘法中是否也有这样的定律呢？我们一起来研究。
３、下面每组算式左右两边的结果相等吗？0.7×1.2○1.2×0.7(0.8×0.5)○0.8×(0.5×0.4)(2.4＋3.6)○2.4×0.5＋3.6×0.5(1)集体观察一下0.7×1.2与1.2×0.7相等吗？为什么？(2)以小组为单位，通过看看、想想、算算的'方法解决下面两题(3)交流汇报讨论结果(4)说明：整数乘法的交换律、结合律和分配律，对于小数乘法同样适用。
去年与今年百分比计算方法
去年子跟今年子比，算那个百分比，其实简单得很嘛。
就跟你做菜加盐巴一样，多一点点少一点点，味道就差老远了。
首先嘞，你得晓得去年是好多，今年又是涨了好多或者降了好多。
打个比方，去年你卖了100个苹果，今年卖了120个。
要算涨了多少百分比，就用今年比去年多的数量，也就是20个，除以前年的数量100个，然后再乘以100%。
这么一算，(20/100)x100%=20%，哦豁，今年销量涨了百分之二十，喜人得很嘛！
但要是今年卖得不如去年呢，比如只卖了80个，那你就用去年减今年的差值，也就是20个，还是除以前年的数量100个，不过这次结果前面要加个负号，表示是降了。
(20/100)x100%=-20%，嚯哟，今年销量降了百分之二十，那就要找找原因，想办法了。
看嘛，百分比计算就这么回事儿，关键是要找准基数，也就是去年那个数，然后加减乘除一套组合拳打下来，结果就明明白白摆在你面前了。
四川话讲起来，是不是感觉更接地气，更好懂了呢？。
Practice Questions and Answers from Lesson I-7: ElasticityThe following questions practice these skills:✓Use the midpoint method for calculating percent change.✓Compute price elasticity of demand.✓Identify elastic and inelastic demand according to the price elasticity of demand.✓For elastic demand, apply the negative relation between price and revenue.✓For inelastic demand, apply the positive relation between price and revenue.✓Remember demand is more elastic when there are more substitutes or closer substitutes.✓Compute the price elasticity of supply.✓Compute cross-price elasticities of demand.✓Relate cross-price elasticities of demand to gross substitutes and gross complements.✓Identify elastic and inelastic portions of a linear demand curve.✓Compute income elasticity of demand.Question: , the online bookseller, wants to increase its total revenue. One strategy is to offer a 10% discount on every book it sells. knows that its customers can be divided into two distinct groups according to their likely responses to the discount. The accompanying table shows how the two groups respond to the discount.a. Using the midpoint method, calculate the price elasticities of demand for group A and group B.b. Explain how the discount will affect total revenue from each group.c. Suppose knows which group each customer belongs to when he logs on and can choose whether or not to offer the 10% discount. If wants to increase its total revenue, should discounts be offered to group A or to group B, to neither group, or to both groups?Answer to Question:a. Using the midpoint method, the percent change in the quantity demanded by group A is1.65 million - 1.55 million 0.1 million−−−−−−−−−−−−−−−−−−−−−−−− x100 = −−−−−−−−− x 100 = 6.25%(1.55 million + 1.65 million)/2 1.6 millionand since the change in price is 10%, the price elasticity of demand for group A is6.25%/10% = 0.625Using the midpoint method, the percent change in the quantity demanded bygroup B is1.7 million - 1.5 million 0.2 million−−−−−−−−−−−−−−−−−−−−−−−− x100 = −−−−−−−−− x 100 = 12.5%(1.5 million + 1.7 million)/2 1.6 millionand since the change in price is 10%, the price elasticity of demand for group B is12.5%/10% = 1.25b. For group A, since the price elasticity of demand is 0.625 (demand is inelastic), total revenue will decrease as a result of the discount. For group B, since the price elasticity of demand is 1.25 (demand is elastic), total revenue will increase as a result of the discount.c. If wants to increase total revenue, it should definitely not offer the discount to group A and it should definitely offer the discount to group B.Question: Do you think the price elasticity of demand for Ford sport-utility vehicles (SUVs) will increase, decrease, or remain the same when each of the following events occurs? Explain your answer.a. Other car manufacturers, such as General Motors, decide to make and sell SUVs.b. SUVs produced in foreign countries are banned from the American market.c. Due to ad campaigns, Americans believe that SUVs are much safer than ordinary passenger cars.d. The time period over which you measure the elasticity lengthens. During that longer time, new models such as four-wheel-drive cargo vans appear.Answer to Question:a. The price elasticity of demand for Ford SUVs will increase because more substitutes are available.b. The price elasticity of demand for Ford SUVs will decrease because fewer substitutes are available.c. The price elasticity of demand for Ford SUVs will decrease because other cars are viewed as less of a substitute.d. The price elasticity of demand for Ford SUVs will increase over time because more substitutes (such as four-wheel-drive cargo vans) become available.Question: The accompanying table gives part of the supply schedule for personal computers in thea. Calculate the price elasticity of supply when the price increases from $900 to $1,100 using the midpoint method.b. Suppose firms produce 1,000 more computers at any given price due to improved technology. As price increases from $900 to $1,100, is the price elasticity of supply now greater than, less than, or the same as it was in part a?c. Suppose a longer time period under consideration means that the quantity supplied at any given price is 20% higher than the figures given in the table. As price increases from $900 to $1,100, is the price elasticity of supply now greater than, less than, or the same as it was in part a?Answer to Question:a. Using the midpoint method, the percent change in the quantity supplied is12,000 – 8,000 4,000−−−−−−−−−−−−−−−−−− x100 = −−−−−−−− x 100 = 40%(12,000 + 8,000)/2 10,000and the percent change in the price is$1,100 - $900 $200−−−−−−−−−−−−−−−− x100 = −−−−−−− x 100 = 20%($1,100 + $900)/2 $1,000The price elasticity of supply is therefore40%/20% = 2b. The elasticity estimate would be lower. A price change from $900 to $1,100 is a 20% price change, just as calculated in part a. Previously, when the quantity supplied changed from 8,000 to 12,000, that was a 40% change in the quantity supplied. Now that the quantity supplied at each price is higher by 1,000, the same price change would imply a change in the quantity supplied from 9,000 to 13,000, which is a 36% change using the midpoint method. The new price elasticity of supply is 36%/20% = 1.8, which is lower than in part a.c. The elasticity estimate would be unchanged. The price increase from $900 to $1,100 is a 20% increase, just as calculated in part a. But now that all quantities are 20% higher, the quantity supplied increases from 9,600 to 14,400. Using the midpoint method, this is an increase of 14,400 – 9,600 4,800−−−−−−−−−−−−−−−−−− x100 = −−−−−−−− x 100 = 40%(14,400 + 9,600)/2 12,000so that the price elasticity of supply is40%/20% = 2Therefore the price elasticity of supply is the same as in part a.Question: The accompanying table lists the cross-price elasticities of demand for several goods, where the percent quantity change is measured for the first good of the pair, and the percent pricechange is measured for the second good.a. Explain the sign of each of the cross-price elasticities. What does it imply about the relationship between the two goods in question?b. Compare the absolute values of the cross-price elasticities and explain their magnitudes. For example, why is the cross-price elasticity of McDonald’s burgers and Burger King burgers less than the cross-price elasticity of butter and margarine?c. Use the information in the table to calculate how a 5% increase in the price of Pepsi affects the quantity of Coke demanded.d. Use the information in the table to calculate how a 10% decrease in the price of gasoline affects the quantity of SUVs demanded.Answer to Question:a. A negative cross-price elasticity of demand implies that the two goods are gross complements. So air-conditioning units and kilowatts of electricity are gross complements, as are sport-utility vehicles and gasoline. A positive cross-price elasticity of demand implies that the two goods are gross substitutes. So Coke and Pepsi are gross substitutes, as are McDonald’s and Burger King burgers as well as butter and margarine.b. The larger (and positive) the cross-price elasticity of demand is, the more closely the two goods are gross substitutes. Since the cross-price elasticity of butter and margarine is larger than the cross-price elasticity of McDonald’s burgers and Burger King burgers, butter and margarine are closer gross substitutes than are McDonald’s and Burger King burgers. Similarly, the greater (and negative) the cross-price elasticity of demand is, the more strongly the two goods are gross complements.c. A cross-price elasticity of 0.63 implies that a 1% increase in the price of Pepsi would increase the quantity of Coke demanded by 0.63%. Therefore, a 5% increase in the price of Pepsi would increase the quantity of Coke demanded by five times as much, that is, by 5 × 0.63% = 3.15%.d. A cross-price elasticity of −0.28 implies that a 1% fall in the price of gasoline would increase the quantity of SUVs demanded by 0.28%. Therefore, a 10% fall in the price of gasoline would increase the quantity of SUVs demanded by 10 times as much, that is, by 10 × 0.28% = 2.8%.Question: What can you conclude about the price elasticity of demand in each of the following statements?a. “The pizza delivery business in this town is very competitive. I’d lose half my customers if I raised the price by as little as 10%.”b. “I owned both of the two Jerry Garcia autographed lithographs in existence. I sold one on eBay for a high price. But when I sold the second one, the price dropped by 80%.”c. “My economics professor has chosen to use the Krugman/Wells textbook for this class. I have nochoice but to buy this book.”d. “I always spend a total of exactly $10 per week on coffee.”Answer to Question:a. This statement says that a 10% increase in price reduces the quantity demanded by 50%. That is, the price elasticity of demand is-50%/10% = -5So demand is elastic.b. The fact that it was necessary for price to drop by 80% in order to sell one more unit (an increase in quantity of 67%, using the midpoint method) indicates that the demand for Jerry Garcia autographed lithographs is inelastic.c. There is no substitute available, so demand is inelastic. (Although, over time, as more used Krugman/Wells textbooks become available, the price elasticity of demand will increase.)d. Demand is unit-elastic: no matter what the price of coffee is, the total revenue to the producer (which is my total expenditure on coffee) remains the same.Question: The accompanying table shows the price and yearly quantity sold of souvenir T-shirts in the town of Crystal Lake according to the average income of the tourists visiting.from $5 to $6 and the average tourist income is $20,000. Also calculate it when the average tourist income is $30,000.b. Using the midpoint method, calculate the income elasticity of demand when the price of a T-shirt is $4 and the average tourist income increases from $20,000 to $30,000. Also calculate it when the price is $7.Answer to Question:a. Suppose the average tourist income is $20,000. Using the midpoint method, the percent change in the quantity demanded is1,600 – 2,400 -800−−−−−−−−−−−−−−−−−− x100 = −−−−−−− x 100 = -40%(1,600 + 2,400)/2 2,000and the percent change in the price is$6 - $5 $1−−−−−−−−−−− x100 = −−−−− x 100 = 18.2%($6 + $5)/2 $5.5The price elasticity of demand is therefore40%/18.2% = 2.2Now suppose the average tourist income is $30,000. The percent change in the quantity demanded is3,000 – 4,200 -1,200−−−−−−−−−−−−−−−−−− x100 = −−−−−−− x 100 = -33.3%(3,000 + 4,200)/2 3,600and the percent change in the price is$6 - $5 $1−−−−−−−−−−− x100 = −−−−− x 100 = 18.2%($6 + $5)/2 $5.5The price elasticity of demand is therefore33.3%/18.2% = 1.8b. Suppose the price of a T-shirt is $4. Using the midpoint method, the percent change in the quantity demanded is5,000 – 3,000 2,000−−−−−−−−−−−−−−−−−− x100 = −−−−−−− x 100 = 50%(5,000 + 3,000)/2 4,000and the percent change in income is$30,000 - $20,000 $10,000−−−−−−−−−−−−−−−−−−−− x100 = −−−−−−−− x 100 = 40%($30,000 + $20,000)/2 $25,000The income elasticity of demand is therefore50%/40% = 1.25Now suppose the price of a T-shirt is $7. Using the midpoint method, the percent change in the quantity demanded is1,800 – 800 1,000−−−−−−−−−−−−−−−− x100 = −−−−−−− x 100 = 76.9%(1,800 + 800)/2 1,300and the percent change in income is, as before,$30,000 - $20,000 $10,000−−−−−−−−−−−−−−−−−−−− x100 = −−−−−−−− x 100 = 40%($30,000 + $20,000)/2 $25,000The income elasticity of demand is therefore76.9%/40% = 1.9Question: In each of the following cases, do you think the price elasticity of supply is(i) perfectly elastic; (ii) perfectly inelastic; (iii) elastic, but not perfectly elastic; or(iv) inelastic, but not perfectly inelastic? Explain using a diagram.a. An increase in demand this summer for luxury cruises leads to a huge jump in the sales price of a cabin on the Queen Mary 2.b. The price of a kilowatt of electricity is the same during periods of high electricity demand as during periods of low electricity demand.c. Fewer people want to fly during February than during any other month. The airlines cancel about 10% of their flights as ticket prices fall about 20% during this month.d. Owners of vacation homes in Maine rent them out during the summer. Due to the soft economy this year, a 30% decline in the price of a vacation rental leads more than half of homeowners to occupy their vacation homes themselves during the summer.Answer to Question:a. Supply is perfectly inelastic: the quantity of cabins on the Queen Mary 2 is fixed. As demand increases (a rightward shift in the demand curve), the price of a cabin on the Queen Mary 2 increases, without an increase in the quantity supplied. See the accompanying diagram.b. Supply is perfectly elastic. As demand changes (for instance, as demand increases in times of high electricity demand), price does not change but the quantity supplied does change.c. Supply is inelastic. As price falls by 20%, the quantity supplied falls by 10%. This implies a price elasticity of supply of10%/20% = 0.5which is inelastic. See the accompanying diagram.d. Supply is elastic. As price falls by 30%, the quantity supplied falls by more than 50%. This implies a price elasticity of supply greater than50%/30% = 1.7.See the accompanying diagram.Question: Taiwan is a major world supplier of semiconductor chips. A recent earthquake severely damaged the production facilities of Taiwanese chip-producing companies, sharply reducing the amount of chips they could produce.a. Assume that the total revenue of a typical non-Taiwanese chip manufacturer rises due to these events. In terms of an elasticity, what must be true for this to happen? Illustrate the change in total revenue with a diagram, indicating the price effect and the quantity effect of the Taiwan earthquake on this company’s total revenue.b. Now assume that the total revenue of a typical non-Taiwanese chip manufacturer falls due to these events. In terms of an elasticity, what must be true for this to happen? Illustrate the change in total revenue with a diagram, indicating the price effect and the quantity effect of the Taiwan earthquake on this company’s total revenue.Answer to Question:a. If the increase in price results in an increase in total revenue, then the price effect (which tends to increase total revenue) must outweigh the quantity effect (which tends to reduce total revenue). That is, demand must have been inelastic. In the accompanying diagram, as supply shifted leftward from Sto1 , the fall in total revenue due to the quantity effect (area A) is outweighed by the gain in total revenue S2due to the price effect (area B).b. If the increase in price results in a fall in total revenue, then the quantity effect (which tends to reduce total revenue) must outweigh the price effect (which tends to increase total revenue). That is, demandmust have been elastic. In the accompanying diagram, as supply shifted leftward from S1 to S2, totalrevenue falls by the amount of the quantity effect (area A) but rises by the amount of the price effect (area B). The quantity effect (area A) is larger than the price effect (area B) so total revenue declines.Question: There is a debate about whether sterile hypodermic needles should be passed out free of charge in cities with high drug use. Proponents argue that doing so will reduce the incidence of diseases, such as HIV/AIDS, that are often spread by needle sharing among drug users. Opponents believe that doing so will encourage more drug use by reducing the risks of this behavior. As an economist asked to assess the policy, you must know the following: (i) how responsive the spread of diseases like HIV/AIDS is to the price of sterile needles and (ii) how responsive drug use is to the price of sterile needles. Assuming that you know these two things, use the concepts of price elasticity of demand for sterile needles and the cross-price elasticity between drugs and sterile needles to answer the following questions.a. In what circumstances do you believe this is a beneficial policy?b. In what circumstances do you believe this is a bad policy?Answer to Question:a. Handing out free needles lowers the price of needles to zero. First consider thedemand for needles. The higher the price elasticity of demand for sterile needles, the greater the increase in the quantity of sterile needles demanded in response to a decrease in the price. And the greater the increase in the quantity of sterile needles demanded, the lower the spread of diseases like HIV/AIDS. Now consider the demand for drugs. Drugs and sterile needles are gross gross complements: as the price of sterile needles falls, the demand for drugs increases. This implies that the cross-price elasticity of demand between drugs and sterile needles is negative. The less negative (the closer to zero) the cross-price elasticity of demand between drugs and sterile needles, the lessresponsive is the demand for drugs to the price of sterile needles. So the policy would be beneficial if the price elasticity of demand for sterile needles is high (elastic) and the cross-price elasticity of demand between drugs and sterile needles is negative and low (close to zero, that is, weakly complementary).b. Similar reasoning as in part a implies that the policy would be a bad idea if the price elasticity of demand for sterile needles is low (inelastic) and the cross-price elasticity of demand between drugs and sterile needles is high and negative (strongly complementary).Question: Worldwide, the average coffee grower has increased the amount of acreage under cul-tivation over the past few years. The result has been that the average coffee plantation produces significantly more coffee than it did 10 to 20 years ago. Unfortunately for the growers, however, this has also been a period in which their total revenues have plunged. In terms of an elasticity, what must be true for these events to have occurred? Illustrate these events with a diagram, indicating the quantity effect and the price effect that gave rise to these events.Answer to Question: An increase in the amount of acreage that is cultivated results in a rightward shift in the supply of coffee. This reduces the price of coffee and increases the quantity demanded. If total revenue from coffee sales have decreased, this means that the price effect (which tends to lower total revenue) must have outweighed the quantity effect (which tends to increase total revenue). This implies that demand must be inelastic. As shown in the accompanying diagram, the price effect results in a loss of total revenue equal to the size of area A. The quantity effect (the quantity demanded increases as a result of the price fall) results in an increase in total revenue equal to the size of area B. Area A exceeds area B, so total revenue falls.Question: The U.S. government is considering reducing the amount of carbon dioxide that firms are allowed to produce by issuing a limited number of tradable allowances for carbon dioxide (CO)2 emissions. In an April 25, 2007, report, the U.S. Congressional Budget Office (CBO) argues that “mostemissions would be borne by consumers, who would faceof the cost of meeting a cap on CO2persistently higher prices for products such as electricity and gasoline . . . poorer households would bear a larger burden relative to their income than wealthier households would.” What assumption about one of the elasticities you learned about in this chapter has to be true for poorer households to be disproportionately affected?Answer to Question: For poorer households to be disproportionately affected by an increase in energy prices, it is necessary that those households spend a larger share of their income on energy products than wealthier households. In other words, as income rises, the quantity of energy productsPractice Questions and Answers from Lesson I-7: Elasticitydemanded has to increase less than proportionately. So the CBO must think that the income elasticity of demand for energy products, although positive, is less than 1: energy products are income-inelastic. In fact, this is just what the CBO report says: “lower-income households tend to spend a larger fraction of their income than wealthier households do and . . . energy products account for a bigger share of their spending.”Question: According to a Honda press release on October 23, 2006, sales of the fuel-efficientfour-cylinder Honda Civic rose by 7.1% from 2005 to 2006. Over the same period, according to data from the U.S. Energy Information Administration, the average price of regular gasoline rose from $2.27 per gallon to $2.57 per gallon. Using the midpoint method, calculate the cross-price elasticity of demand between Honda Civics and regular gasoline. According to your estimate of the cross-price elasticity, are the two goods gross complements or gross substitutes? Does your answer make sense? Answer to Question: An increase in price from $2.27 to $2.57, using the midpoint method, is a percent increase of$2.57 - $2.27 $0.30−−−−−−−−−−−−−−−− x100 = −−−−−− x 100 = 12.4%($2.57 + $2.27)/2 $2.42So the cross-price elasticity of demand is7.1%/12.4% = 0.6Since the cross-price elasticity of demand between Honda Civics and regular gasoline is positive, your estimate says that the two are gross substitutes. This answer might seem perplexing because cars and gasoline are generally gross complements: you need gasoline to run a (gasoline-powered) car like a Honda Civic. So the complementary relationship between gas and cars implies that the cross-price elasticity between them is negative. But a Honda Civic adds another dimension to the comparison: it is a fuel-efficient car, not a gas-guzzler. And fuel-efficient cars and gas guzzlers are gross substitutes. So as gasoline prices rise, the demand for gas-guzzling cars falls and the demand for fuel-efficient cars (such as the Honda Civic), which are gross substitutes, rises. So the substitute nature betweengas-guzzlers and Honda Civics implies a positive cross-price elasticity between gas and Honda Civics. Which effect is stronger? Clearly it is the substitution effect that is stronger, because the data show a positive cross-price elasticity.11。
常用纸张尺寸大小现在纸张的规格很多，基本的有四种：（全张尺寸）1、787*1092MM2、850*1164MM3、889*1196MM4、880*1230MM还有很多不规则的全张尺寸。
所说的A*的尺寸是国际流行尺寸，即我们俗称的“大度尺寸”，最好用3，4两种裁切。
A2的尺寸是420*594MM，用3，4两种尺寸的全张可以裁切出A2的四张。
纸张的规格是指纸张制成后，经过修整切边，裁成一定的尺寸。
过去是以多少"开"（例如8开或16开等）来表示纸张的大小，现在我采用国际标准，规定以A0、A1、A2、B1、B2......等标记来表示纸张的幅面规格。
标准规定纸张的幅宽（以X表示）和长度（以Y表示）的比例关系为X：Y=1：n 。
按照纸张幅面的基本面积，把幅面规格分为A系列、B系列和C系列，幅面规格为A0的幅面尺寸为841mm×1189mm，幅面面积为1平方米；B0的幅面尺寸为1000mm×1414mm，幅面面积为2.5平方米；C0的幅面尺寸为917mm×1279mm，幅面面积为2.25平方米；复印纸的幅面规格只采用A系列和B系列。
若将A0纸张沿长度方式对开成两等分，便成为A1规格，将A1纸张沿长度方向对开，便成为A2规格，如此对开至A8规格；B8纸张亦按此法对开至B8规格。
A0～A8和B0～B8的幅面尺寸见下表所列。
其中A3、A4、A5、A6和B4、B5、B6等7种幅面规格为复印纸常用的规格。
举例说明：“A4”纸，就是将A型基本尺寸的纸折叠4次，所以一张A4纸的面积就是基本纸面积的2的4次方分之一，即1/16。
其余依此类推。
A类就是我们通常说的大度纸，整张纸的尺寸是889*1194mm，可裁切A1(大对开，570*840mm）、A2（大四开，420*570mm）、A3（大八开，285*420mm）、A4（大十六开，210*285mm）、A5（大三十二开，142.5*210mm）……；B类就是我们通常说的正度纸，整张纸的尺寸是787*1092mm，可裁切B1(正对开，520*740mm）、B2（正四开，370*520mm）、B3（正八开，260*370mm）、B4（正十六开，185*260mm）、B5（正三十二开，130*185mm）……。
计算公式什么要乘100在数学中，有很多不同的公式和计算方法。
有时候我们会遇到一些需要乘以100的情况，那么为什么要乘以100呢？这个问题可能会让很多人感到困惑。
在本文中，我们将探讨一些常见的情况，为什么需要乘以100以及这种计算方法的意义。
首先，让我们来看一些常见的情况，为什么需要乘以100。
在日常生活中，我们经常会遇到百分比、利率、比率等概念。
这些概念都涉及到乘以100的计算。
例如，当我们计算百分比时，我们会将小数乘以100来得到百分比的值。
同样，当我们计算利率或者比率时，也需要将小数乘以100来得到相应的百分比值。
那么为什么需要乘以100呢？这其实涉及到百分比的定义。
百分比是将一个数表示为另一个数的百分之几。
例如，如果我们说某个数是10%，那么这个数其实就是另一个数的百分之十。
而百分之十就是10/100，所以我们需要将这个数乘以100来得到百分比的值。
除了百分比之外，乘以100还有其他的意义。
在金融领域，利率是一个非常重要的概念。
利率是指借款人需要支付给贷款人的利息。
当我们计算利率时，我们通常会将利率表示为百分比。
这样做的好处是可以更直观地理解利率的大小。
同时，乘以100也可以方便我们进行计算，因为百分比通常是以百分之一为单位来计算的。
除此之外，在统计学和经济学中，比率也是一个重要的概念。
比率是指两个数量之间的比较。
当我们计算比率时，通常也会将结果表示为百分比。
这样做的好处是可以更清晰地了解两个数量之间的关系。
同时，乘以100也可以帮助我们更容易地进行比较和分析。
总的来说，乘以100是为了更直观地表示数值，并且方便进行计算和比较。
百分比、利率、比率等概念都需要乘以100来表示，这样可以更清晰地了解数值的大小和关系。
在实际应用中，乘以100的计算方法也是非常常见的，因此我们需要掌握这种计算方法的意义和应用。
在日常生活中，我们经常会遇到需要乘以100的情况。
无论是在金融领域、统计学领域还是其他领域，乘以100都是一个非常常见的操作。
庆祝XXX成立100周年观后感【四篇】.doc今天是XXX100周年华诞，我看了一部庆祝党的成立的影片，深受感动。
自1921年至今，XXX一直坚持不懈地为中国人民谋求幸福，经历了风雨洗礼，但和追求从未改变。
作为党员，我们应该思考如何在平凡的工作中作出不平凡的贡献，以无愧于党员的称号。
在XXX的领导下，中国犹如一只浴火重生的凤凰，摆脱了三座大山的枷锁，展现出勤劳和智慧的翅膀，在改革和开放的大潮中蓬勃发展。
作为普通的党员，我们感到骄傲和自豪，但也应该肩负起重任，为人民的利益奉献自己的青春和生命。
战火已经远去，但和平年代仍然面临着新的挑战。
XXX 之所以能够在艰苦的环境中带领全国人民不断前进，是因为他是一个属于人民的政党，人民的利益高于一切。
党员是一面旗帜，是一面引领人民群众走向富裕的旗帜，是一面让所有的贪欲、腐朽汗颜的旗帜。
我们欣喜地看到一面面鲜红的党旗正在全国各条战线上高高飘扬，人民不会忘记那些为人民利益抛头颅洒热血的战士，不会忘记在震后废墟中用自己的双手拯救生命的天使，更不会忘记五星红旗在香港、澳门上空升起的时刻。
他们已经化为一抹鲜艳的红色融入了党旗之中，中华民族的凝聚力让世界瞩目！作为一名普通的人民教师，我为自己能够成为文化和精神的传播者以及人类灵魂的塑造者而感到自豪。
我们不仅传授专业知识和技能，更重要的是将中华民族的传统美德传承下去。
作为中国共产。
我身边有太多优秀的同志，他们激励着我不断完善自己，无愧于人民，无愧于党。
这是我一生追求和奋斗的目标。
作为一名中国员，我们要重温入党誓言，以为共产主义事业奋斗终身的名义再次向人民郑重宣誓。
党是中华民族的英勇和守护神。
没有党，我们中华民族也许到今天依旧是一个黑暗的旧中国。
历史告诉我们，在封建主义和帝国主义的多重压迫之下，是我们的XXX英勇地解决了人民的困境，创造了惊天动地的二万五千里长征，锻造了XXX伟大的革命精神。
战中的浴血奋战，向全世界表明中国人民不可辱，中华民族不可欺。
整百乘一位数讲解一、整百乘一位数的意义： 20×5=100。
二、整百乘法的特点：1．都是从个位开始乘，且都是两位数。
2．都要进行相应的十进位加或减法。
3．都能约分。
4．都有积变小的现象。
三、简便计算：（ 1）连续两次积末尾共有4个0，其中第二个0去掉得到的两位数乘一位数，即24×4=16（ 2） 25×3= 125。
四、注意事项：（ 1）整百数乘整百数应从个位乘起。
20×5=100。
100×8=800。
（ 2）如果整百数末尾有多余的0，用这些多余的0依次去掉。
如： 100×5=400，积不变。
若把5个百位上的5个0都拿走，那么得到的是400×5=3000。
（ 3）小数乘整百数时，小数点要和整百数的小数点对齐。
如： 20×8=80。
80×0=8。
（ 4）两位数乘整百数积可能会变小。
8×1=8。
（ 5）整百数乘整百数要从个位乘起。
若不够100，可以向前一位进1。
如： 2×7=14。
7×2=14。
五、解决问题的策略：1.将多个整百数合并成一个整百数来解决问题。
2.先看一下所给的多个整百数之间的差是否都是一个整百数。
如果是的话就要用转化的方法。
3.如果整百数与某一位的一个数之和大于100，那么用“被除数÷除数=商”来解决问题。
如：已知3位数350÷4=150， 4位数650÷5=70，一共是150×4=600； 5位数100×4=400，一共是400×5=2000。
4.当个位不是百位时，用整百数减去多出的部分，再加上一个整百数。
5.当个位数字为1、 6、 9时，只用去掉后面一个0，个位变为0，然后用这个整百数减去一个数，最后在十位上加上另一个整百数。
如： 6×5=30，只去掉个位的5就变为30， 10-5+0=30。
为什么要乘100%
为什么要乘100%
⽂/春秋书⽣
有的学⽣问：在求百分率的时候，为什么要乘100%？要回答这个问题，⾸先要知道 “率”指什么？
“率”是两个数相除的商所化成的百分数，即百分⽐或百分率。
百分率是表⽰两个数的⽐，是没有单位名称的。
⽣活中⽤百分率进⾏统计的还很多，例如学⽣的出勤率、花⽣仁出油率、学⽣考试的及格率、投球的命中率、油菜⼦出油率、产品的合格率、⼩麦的出粉率等。
教材84页以出勤率的含义，使学⽣明⽩：求出勤率就是求“出勤学⽣的⼈数占总⼈数的百分之⼏”，所以⽤除法计算。
在此基础上教材给出了求出勤率的计算公式，出勤率 =(出勤学⽣⼈数/学⽣总⼈数)×100%，在这个公式中，很多学⽣不明⽩为什么要
乘100%？因此，要弄清为什么要乘100%的道理，是本节课的⼀个重点，因为出勤率是百分率的⼀种，公式本⾝应该⽤百分数的形式（%）表⽰。
如果公式单写成“达标率=达标学⽣⼈数/学⽣总⼈数”只是分数形式，⽽不是百分数。
如果在“出勤率 =了，出勤学⽣⼈数/学⽣总⼈数”的后⾯添上“×100%”（相当于×1），就可以既使数值不变，⽽⼜是百分数的形式。
洪绪镇小学语文“100%动感课堂”教学模式基本流程一、“100%动感课堂”教学模式基本内涵模式的核心思想是自主、合作、探究，让“每个孩子”参与其中，把班级集体学习改为小组学习，把个人展示改为小组展示，把评价个人改为评价小组，让孩子们的身体、思维、智慧、情感等真正“动”起来，最大限度地实现小班化课堂教学的“四个百分百”，即：100%关注，100%互动，100%展示，100%提升，这也是“100%动感课堂”的基本目标。
本模式分为三个学习环节，八个基本步骤：环节一：认识——自主阅读，整体把握（以学生自主阅读为主，教学内容主要指向陈述性知识。
导课目标→双基检测→整体感知）环节二、实践——重点突破，语意兼得：（抓住语文本体性教学内容，针对教学重点、难点展开教学。
自主学习→合作探究→展示交流）环节三、总结——积累拓展，读写训练（注重培养学生学习反思总结能力评价提升→达标检测）二、“100%动感课堂”教学模式基本流程环节一：认识——自主阅读，整体把握（以学生自主阅读为主，教学内容主要指向陈述性知识。
）1.导课明标操作步骤：A、导课：教师用简洁的语言根据授课内容和特点，通过联系社会与生活实际素材或拓展深化已有知识等手段，创设问题情景导入课题，调动起学生学好本节课的欲望，引导学生积极思维、大胆质疑（问题驱动）。
教师应注意，教学风格可以不同，但是要服务于教学目的。
（动点：根据情况，尽量吸引学生参与，学生能动起来更好）。
B、明标：即明确学习目标，就是本堂课要达成的知识目标，越简短越好（一般1—3条），可概括地写在黑板上或出示在多媒体上，也可不出示，但师生必须清楚，这是一堂课师生思维行走的方向。
一二年级可采用闯关的形式，把一个个目标变成一个个关，把每一个教学指导变成小妙招。
从而落实明标环节。
（动点：可让学生独读或群读目标，也可让学生说说达到目标应该怎么去学习）。
C双基检测：教师采用听写、提问、板演、交流等方式全面检测学生基础知识，以了解学生自学的各方面情况。
可采用小组互相检查、小组竞赛等方式给予学生适当的评价与反馈。
教师应给学生充分展现自我的平台，注意发现学生在自学过程中出现的问题，并对错误的理解予以纠正。
同时注意发挥学生的主动性，激发学生的学习兴趣。
（动点：小组互相检查、小组竞赛等方式）D在学生熟读课文的基础上，引导学生对文章的主体事件、形象、情感、基调等建立初步的整体感知。
培养学生整体把握文本的能力，尤其是中段阅读教学应将培养学生整体把握文本的能力作为重点教学内容扎实落实。
（动点：小组、互相交流、小组汇报等方式。
）实施策略：（1）方法：教师将教学目标按照课时安排分解，通过课前制作好的投影或黑板让学生看。
（2）目的：让学生整体上知道本课时的学习任务和要求。
（3）意义：a、使学生在上课开始就明确学习目标和学习方向，同时激发学生的学习兴趣，调动学生学习的积极性，促进学生在以后的各环节里主动地围绕目标探索追求。
b、由于学习目标往往是一节课的主干知识及要求的体现，因此，长期坚持揭示目标，可以培养学生的概括能力。
（4）注意事项：a、要认真钻研教材和课程标准，准确制定学习目标，各个课时的分目标要与总目标对应衔接，切实做到既不能拨高要求，也不能降低要求。
b、学习目标要层次清楚，简明扼要，外显可测。
c、要引导学生认真默看，不要急于切换投影或拿开小黑板。
d、本环节的关键是目标准确，主要通过集体备课的形式解决。
环节二、实践——重点突破，语意兼得：（抓住语文本体性教学内容，针对教学重点、难点展开教学。
2.自主学习操作步骤：A、出示自学指导。
应抓住学法指导是指导学生根据达成目标，采取相应学法一步一步地去学，是学生学习的路线图。
让学生清楚做什么、甚至怎么去做，把要做的问题一项一项地展现给学生（展现的方法自定），让学生逐个地去探索研究撰写（一、二年级可逐个问读一读、说一说、评一评、练一练等方法循环学习），甚至一些练习题、拓展题（三维题）也可出示。
学法指导设计一定紧扣目标。
（动点：可以教师读、群体默读学法指导。
）B、独立学习。
按照自学指导，学生个体独自学习，让学生自己感知哪些问题已经明白了，哪些问题还不会，以便在对学、群学中寻求帮助。
同时，独学是为了对学、群学、展示做准备，自己不深入学习，就无法发言、交流和展示，想展示好（人之本能）就必须先深入学好，这也是一种压力。
特别提醒的是：整堂课或某个知识点，独学是不可或缺的环节。
否则，学习就不是学生自己的事了。
教师应该深入到各个小组，帮助学困生。
（动点：独学中不懂不会的问题，随时可以问“对子”、问组员、问老师，允许下位）。
实施策略：（1）方法：教师明确学习的步骤及要方法，通过课前制作好的投影或黑板让学生看。
学生自学时，教师要融入学生中，及时解答学生的询问。
教师针对学生在交流反馈过程中出现的问题，落实到本体性教学内容上，引导学生通过同伴互助和师生交流的方式解疑，精心设计问题组织教学，突破重难点。
应注重语文知识内涵与外延的挖掘及与学过知识的联系；要注重知识的拓展与提升，澄清学生思维认识上的疑、难点。
以生为本，让学生亲历学习过程。
重视“得”（2）目的：让学生自我感知、自主生成，为合作探究、展示交流储备思想和语言。
（3）意义：a、让学生带着明确的任务，掌握恰当的自学方法从而使自学更有效。
b、坚持每次自学前都给予方法指导，使学生积累了不少自学方法，学生的自学能力必然提高。
注意事项：a、明确自学内容，即让学生知道学什么。
有的教材内容单一，一般一次性自学；有的教材内容多，可视情况分几次自学，但每次自学都必须写清楚自学的内容（范围）。
b、明确自学的方法。
例如，看书理解边看书边与同桌讨论，看注释等，发现疑难问题做记号。
c、明确自学后的要求，即用多长时间，应达到什么要求，届时如何检测。
d、重点巡视中差学生，可以给后进生说几句悄悄话，帮助端正自学态度，使他们也变得认真起来。
e语文知识、语文策略（方法）和语文技能。
这类教学内容是语文课程必须承担的本职任务，反映出语文课程区别于其他课程的本质特性，完成这些教学内容，就能为学生学习各门课程奠定扎实的基础，也能为学生人文素养的全面提升奠定基础。
重视文体特点，重视语言的积累和借鉴，重视落实“语用”。
一些“基础性”教学内容每篇课文都需要落实，比如课文中的生字、新词以及课文朗读等等，无论低年级还是中、高年级，务必将这些基础性教学内容的落实放在首要位置，作为一堂课教学的“保底工程”。
中、高年级课文教学除了落实这些基础性教学内容，还需要新授一些其他的语文知识和阅读写作方法，进行必要的语文技能练习，我们将这些新授内容称为“发展性”教学内容让学生经历认知、感受、内化、实践的学习过程，由浅入深，充分展开，从错误走向正确，从朦胧走向清晰，让学生亲历学习过程。
对学生所提较为集中的问题，教师要从原因分析入手，从字词、写作方法、理解的深刻性、全面性方面，引导学生思考，培养学生分析问题和解决问题的能力。
3.合作探究操作步骤：A. 对学：即“对子”两人依据自学指导内容逐一相互交流检查，是互相补充、相互提升的过程，这是最基本的学习单位，也是最有效的学习方式。
不懂不会的问题，多数都能在“对学”中解决。
（动点：“对子”之间可坐可立、可说可演、可争可问、可以下位）。
B. 群学：有两个主要过程，一是依据自学指导，由组长负责主持，让组员或“对子”汇报不懂不会的问题，寻求帮助，组长或学会的组员当即给予解决（不会的问题学生一般不会隐瞒，否则在展示交流中不会或出错，组员会集体责怪）。
二是在解决不会的问题后，小组共同研究或预演展示交流的方法，或按问题分工，每人都展示发言；或选定主要发言人，其他组员负责补充。
（动点：群学过程提倡所有成员站起来凑在一起，可说可演、可争可问、可以下位）。
实施策略：（1）方法：在小组内交流学习成果，要求所有学生都要展示自己解决问题的方案，同学之间可以互相对比解决问题的策略，对争议性问题进行探讨，逐步补充完善，形成小组意见。
（2）目的：在交流、研讨的过程中，不断优化学习成果。
（3）意义：发挥学生的主体精神和协作精神，培养他们的多向思维、求异思维和创新精神。
（4）注意事项：a、小组合作学习教师要适时指导。
b、一节课中合作学习的次数也不易过多，1～2次为易，次数太多，讨论的主题就会分散，每次讨论也只能蜻蜓点水、留于形式。
c、小组合作学习要注意小组成员之间的分工。
（四）展示交流操作步骤：依据自学指导，以小组为单位集体上讲台，对学习成果逐个或全部进行展示，尽可能地让每个小组都有展示的机会。
在每个小组展示完后，本组成员和其他小组成员都可补充评价，教师对表现突出的小组及时进行“星星”评价（包括个人补充评价所在的小组）。
（动点：展示过程能站着的不坐着，能上讲台的不在原位，能演示操作的不只用嘴说，能分角色表演的最好表演。
其他小组成员可下位找最佳位置观看倾听，以方便补充和评价）。
实施策略：1、方法：以小组为单位，用板演或口答的形式对自学获得的知识进行展示，根据回答的情况和学习的目标，教师及时组织交流，让学生在思维的碰撞中自主经历知识的形成过程，自主获得知识和技能。
特别注意多给后进生和中等生创设展示的机会。
2、目的：最大限度地暴露学生自学后存在的疑难问题。
3、意义：若后进生做对了，说明全班学生都会了，就不要老师再教了；若后进生做错了，引导中等偏上的学生分析，讲清错的原因，引导更正，归纳。
这不仅对后进生有帮助，而且使尖子生理解更深刻了。
4、注意事项：a、要解放思想，真正让后进生参与，千万不得搞形式主义，只叫尖子生演练，表面上正确率高，实质上掩盖矛盾，不能最大限度地暴露自学后存在的疑难问题。
b、要面向全体学生，后进生回答问题或板演时，要照顾全体同学，让他们聆听别人回答问题，随时准备纠正错误等。
c、教师要巡视，搜集位上同学有哪些错误，并及时分类，哪些属于新知识方面的，这是要解决的主要矛盾；哪些属于旧知识遗忘或粗心大意的，这是次要矛盾。
把倾向性的错误用投影打出或写在黑板一侧，供评价提升环节使用。
环节三总结——积累拓展，读写结合（注重培养学生学习反思，总结能力）（五）评价提升操作步骤：教师对本节课所学知识进行纠正、补充、系统化，进行必要时对所学知识或情感态度价值观等进行拓展；围绕学习目标，让小组总结评价提升所学收获，并及时进行“星星”评价（让小组都有均等的机会）；师生共同评价本堂课优胜小组（一般评1个），每个小组成员发一张小喜报（组长代表小组领取或分别领取）。
（动点：本环节要关注到后进生的掌握情况，创造机会让他们总结发言，其他学生自由补充，让更多的学生动起来。
）实施策略：1、方法：a、师生对本节课所学知识进行总结、系统、提升、拓展。
b、各小组总结本堂课的收获，让学生对所学知识更有清晰的认识，总结过程要让学生各抒己见，特别是对出现的问题重点点拨。
