In percentages, we often encounter endless situations, so students should know that except for those with specified precision, we usually go to the fourth place after the decimal point, that is, ten thousand places, and then round it to three places after the decimal point. After the percentage is converted, the number before the percentage sign will retain one decimal place. And know that the percentage sign is generally written in decimal form, not in fractional form, such as 33.3%.

(2) How many fractions or percentages a number has is a multiplication problem.

In the new syllabus, the integer application problem added the content of finding the fraction of a number, which was calculated by integer multiplication and division at that time. For example, there are 600 students, nine tenths of whom are young pioneers. How many young pioneers are there? This is to divide 600 people into 10 equal parts, and then multiply by 9 to get the number of people. The formula is: 60010× 9 = 540 (person). With this foundation, students learn the application problems of fractional multiplication, and their thinking is the same, but the method of integer multiplication and division is transformed into fractional multiplication. that is

600 ÷ 10× 9 = 540 (person) is expressed as a fraction.

×9 = 600×540 (person)

Students are required to grasp the conclusion that how much (one percent) of a number is calculated by multiplication.

(3) Know the fraction or percentage of a number and find the division of this number.

This is the inverse problem of fractional multiplication, and it is also a problem that students are easily confused with fractional multiplication. The new syllabus stipulates that scores are the key points.

Learn simple equations before the four operations, and solve them here with column equations to avoid confusion of multiplication and division. Therefore, students are required to find the score of a number and solve the problem with the thinking method of multiplication. For example, the length of a steel pipe is 48 cm. How long is this steel pipe? Students want to: (steel pipe length) × = 48 (cm), let the steel pipe length be x meters, that is, x × = 48 or x = 48, x = 192.

Some problems can be solved by the above methods, or can be considered according to the known quantitative relationship. For example, an engineering team digs caves every hour. How many meters can 1 hour dig caves? Use the above method to solve the problem, let 1 hour dig the cave x meters, the equation is: x = or x =, and the solution is x =. It can also be based on:

Total amount of work ÷ working time = workload per unit time

Therefore, the formula is: ⊙=(m)

The above are the most basic contents in the application questions of fractions and percentages, which students should understand and master.

Second, I can use what I have learned to solve some simple practical problems in my life.

This requirement in the new syllabus is the requirement of the last semester in the primary school stage, and this spirit should also be implemented in the application problems of scores and percentages. According to the limit of no more than three-step calculation, and according to the common problems of scores and percentages in real life, students are generally required to master the following practical problems.

1. Find out what percentage one number has increased or decreased compared with another.

This kind of problem is often used in life and production, for example, the actual output is a few percent more than the planned output, or the electricity consumption this month is a few percent less than last month. Students are required to find the number of increased production (or savings) according to the thinking method of finding the percentage of one number to another, and then compare it with the planned output (or original electricity consumption). The formula is:

(actual output-planned output) ÷ planned output

Or we can first find out what percentage of the actual output is equivalent to the planned output, and then find out what percentage of the increased output is. The formula is:

Actual output ÷ planned output-100% = by what percentage?

This kind of problem has an important concept that students must master. Students know that among integers, 5 is greater than 3 and greater than 2, and 3 is less than 5. However, among the scores and percentages, 5 is greater than 3 = 66.7%, while 3 is not less than 5 times 66.7%, but less than 40%. Because the standard numbers they compare are different, the two percentages are not equal.

2. Find an application problem whose number increases (decreases) by several percent (one percent) and the inverse problem of this kind of problem.

For example, the original 400 young pioneers increased by 12%. How many members are there now? This is the value after asking 400 to increase its 12%. Ask students to answer in two ways:

400+400× 12% = 400+48 = 448 (person);

400× (1+ 12%) = 448 (person).

The inverse problem of this application problem is that there are 448 young pioneers now, which is more than the original 12%. How many young pioneers are there? It is known that a number plus 12% is 448, so this number is needed. Students should understand that the original figure plus the increased number of people 12% is equal to the current figure. Then let it be x-man.

x+ 12%x=448，x=400 .

3. Engineering problems.

This is about the total amount of work, the amount of work per unit time (usually called work efficiency) and working hours. The relationship between the three is:

Working time = total amount of work ÷ workload per unit time