![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
There are some questions about math, science, notation and other things (1) 0.0003 μ M=____ M (2) approximation 0.0070 to___ Bit, there are two significant numbers, they are____ (3) Before May Day, an electrical appliance store opened in a certain area. If 200 of the 1000 prize papers they issued can win, what is the probability that one of them can win____
3x10 ^ - 4 4 7 and 0 1 / 5 after decimal point
Using scientific notation
1. It takes 80 years for a rock to form. Its average thickness is 16.5cm. How many microns does the average monthly rock thickness increase
25000 seeds are only 200 grams, how many grams are there in a seed
1: 80 years = 960 months 16.5/960 = 0.0172 cm = 1.72 x 10 fourth power micron
2: 200 / 50000 = 0.004 g. the scientific counting method is expressed as the negative third power gram of 4 x 10
Forget to adopt
Conversion of several mathematical units! Use scientific notation!
1 km = () nm,
One nanometer = () km
Hello!
1km = (1 * 10 ^ 12) NM
One nanometer = (1 * 10 ^ - 12) km
How to express 1490000 in mathematics by scientific notation
Is it 1.49 * 10 ^ 7 or 0.149 * 10 ^ 8
1.49*10^7
In recent years, due to the increasing desertification and frequent sandstorms, the national life has been seriously affected. In order to prevent sand control, the government has decided to invest funds to encourage farmers to plant trees and grass. According to the calculation, it costs 200 yuan to plant trees and 100 yuan to plant grass per mu. A group of farmers plan to complete the greening task of 2400 mu in one year. In the implementation, due to the actual situation, planting trees has completed 90% of the plan, Planting grass over fulfilled 20% of the plan, just completed the greening task of the plan, so how many trees can be planted with the surplus funds?
If x mu of trees and Y mu of grass are planned to be planted, then
x+y=2400
90%x+120%y=2400
Solution
x=1600
y=800
The reality is that
Tree planting: 1600 * 90% = 1440
Grass planting: 800 * 120% = 960
be
Common fund 1440 * 200 + 960 * 100 = 288000 + 96000 = 384000
Planned capital 1600 * 200 + 800 * 100 = 320000 + 80000 = 400000
Then the remaining 400000-384000 = 16000
It can plant trees 16000 / 200 = 80 mu
However, there is still a large amount of land desertification in China. Can you analyze the reasons
The causes of land desertification can be divided into two types: natural causes and man-made causes. The mechanism of desertification caused by natural causes can be summarized into two points: one is the abnormal global climate change, especially the climate in the middle latitudes is developing towards the direction of warm and dry, which makes the great ecological background conducive to the occurrence of desertification; the other is the existence of a
How much land is desertified in the world every year?
58765 square kilometers
What are the causes of sandstorm and land desertification
Deserts are not entirely formed by wind and sun, but most deserts are formed in the early stage of the earth's formation. High temperature not only makes the earth's surface liquid rock, but also makes the gas state produced by liquid rock, like water vapor, like clouds, shrouded in the sky. At that time, there was also air flow, and there was also cold air as now (in contrast), Similar precipitation is also produced. Similar precipitation makes gaseous rocks produce sediment (grain). Moreover, the distribution of sediment is more uneven than precipitation, which makes the earth produce desert zone
Some molecules at the micro level will diffuse, while some substances at the macro level will diffuse. Desert is a natural phenomenon of diffusion at the macro level. Therefore, land desertification is becoming more and more serious. This phenomenon can only be controlled and worked hard by human beings
Due to excessive deforestation, large areas of grassland reclamation, desertification led to sandstorm weather in our city
What does sandstorm add to the air?
A inhalable particulate matter
B carbon monoxide
C nitrogen dioxide
D sulfur dioxide
But how is the standard answer B, carbon monoxide?
A inhalable particulate matter
Due to excessive deforestation, large area of grassland reclamation and desertification, sandstorm weather appeared in our city, which increased a large number of inhalable particles in the air
What is the cause of sandstorm a land desertification b air pollution C water pollution
A land desertification
A land desertification
RELATED INFORMATIONS
- 1. Sandstorm is a bad weather phenomenon caused by land desertification, which causes great harm to human survival. When sandstorm occurs, the visibility is only tens of meters or even several meters, and the sky turns yellow and dark A. Only the light with shorter wavelength can reach the ground. B. only the light with longer wavelength can reach the ground. C. only the light with higher frequency can reach the ground. D. only the light with lower frequency can reach the ground
- 2. The approximate number is 2.4 × 105____ It's a significant number. It's accurate to___ position
- 3. Arrange the positive and even numbers into 5 columns as follows: column 1, column 2, column 3, column 4, column 5, row 1, row 2, row 2, row 16, 14, 12, 10, row 3, row 2, 30, 28, 26 According to the above arrangement, 2012 should be ranked in () A. Line 502, column 1 B. line 250, column 5 C. line 251, column 4 d. line 252, column 3
- 4. Approximate and significant numbers of rational numbers, The charge of a taxi is 10 yuan when the distance s is less than or equal to 4 km. When the distance s is less than or equal to 15 km, 1.6 yuan will be charged for every 1000 meters and 2.4 yuan for every kilometer. If the distance is less than 1 km, it will be calculated as 1 km. If someone takes this kind of taxi for 14.5 km, it will be RMB yuan. If someone takes this kind of taxi, he will pay 75.6 yuan, The maximum distance is? Km I have to hand in my homework at five
- 5. How many digits are the approximate number of 1.3 billion? How many significant digits are there? How many digits are there? How many significant digits are there?
- 6. Scientific counting approximate significant number What's the exact decile of 0.00000007? How many significant numbers are there
- 7. 2003.20 is an approximate number, which is accurate to () digits and has () significant digits 2.029 * 10 ^ 6, accurate to 10000 bits (), significant number () To train of thought, the day a good score
- 8. Approximate number 2010, 2 significant numbers are reserved__ ?
- 9. How accurate is the approximate number 3300? Better be sure!
- 10. Significant number and approximate number If (a + 1) square + | b-2005 | = 0, then the b-th order of 2006-a=
- 11. What is the third power of the monomial 4xy?
- 12. A small wooden box without cover, measuring from the outside, is 10 cm long, 8 cm wide, 5 cm high, and 1 cm thick. How many square centimeters of 1 cm thick wood board is needed to make this wooden box?
- 13. What is the length and width of the 2.8-inch screen?
- 14. The screen size of a TV set is 24 inches × 16 inches. After the improvement, the length and width of the screen of the TV set will be increased by 20%, and the area will be increased by several percent
- 15. How to convert feet into centimeters
- 16. Print out all the Narcissus numbers. The narcissus number is a three digit number whose cube sum is equal to the number itself Example: 153 = 1 cube + 5 cube + 3 cube
- 17. Use java to find all the "Narcissus numbers" within 1000. The so-called "narcissus number" refers to a three digit number whose cubic sum of each digit is equal to the number itself
- 18. VB programming, if a three digit integer is equal to the cube sum of its digits, then the number is called narcissus number. Enter an integer to judge whether it is narcissus number Private Sub Form_ Load() Dim x%,a%,b%,c%,y% X = InputBox ("please input three digits", "prompt box") If Len(x) = 3 Then a = Val(Mid(x,1,1)) b = Val(Mid(x,2,1)) c = Val(Mid(x,3,1)) y = Val(x) If a ^ 3 + b ^ 3 + c ^ 3 = y Then Print "is Narcissus water" Else Print "not narcissus number" End If Else Print "input error" End If End Sub What's wrong with the above?
- 19. Write VB: "narcissus number" refers to a 3-digit number, the cube sum of each number is equal to the number, such as 153 = 1 ^ 3 + 5 ^ 3 + 3 ^ 3 It must be right Print out all the daffodils between 100 and 1000
- 20. The power of X + 1 of (x-1) is equal to 1. Find the value of X