If the number on a digit of a natural number is 0 or 5, then the number must be a multiple of 5 (2) All even numbers except 2 are composite numbers (3) Even numbers are not multiples of 2 (4) A three digit number composed of 1, 3 and 5 must be a multiple of 3 (5) In nature books, except prime numbers, the rest are composite numbers (6) At least one of three continuous natural numbers is a composite number (7) 1 is the factor of any non-zero natural number (8) Because 8x5 = 40, 8 and 5 are factors and 40 is a multiple (9) The sum of two odd numbers must be even (10) The multiple of a number must be greater than its factor

Judgment questions
(1) If the number on a bit of a natural number is 0 or 5, then the number must be a multiple of 5
(2) All even numbers except 2 are composite numbers
(3) Even numbers are not multiples of 2
(4) A three digit number composed of 1, 3 and 5 must be a multiple of 3
(5) In nature books, except prime numbers, the rest are composite numbers
1 is neither prime nor composite
(6) At least one of three continuous natural numbers is a composite number
1, 2 and 3 are not combined
(7) 1 is the factor of any non-zero natural number
(8) Because 8x5 = 40, 8 and 5 are factors and 40 is a multiple
It should be said that 8 and 5 are factors of 40, and 40 is a multiple of 8 and 5
(9) The sum of two odd numbers must be even
(10) The multiple of a number must be greater than the factor of the number
The number itself is not only its factor, but also its multiple

The least common multiple of any natural number (except 0) and 1 is the number itself

All natural numbers are multiples of one,
Can multiples include zero? Primary school textbooks say: multiples generally do not include 0. Are you math majors or teachers? In other words, is 0 a multiple of 1?

I'm a member of the brigade, believe me. The least common divisor of all natural numbers is 1, that is to say, all natural numbers are multiples of 1

There is a two digit number. The ten digit number is 2 larger than the one digit number. The two digit number is between 50 and 70. Can you work out the two digit number

Suppose the single digit of the two digit is x, then the ten digit is (x + 2). According to the meaning of the question, we get 50 < 10 (x + 2) + x < 70, and the solution is 2811 < x < 4611. Because the single digit should be an integer, so x = 3 or x = 4, and the ten digit is x + 2 = 3 + 2 = 5 or 4 + 2 = 6, so the two digit is 53 or 64

The determinant of the matrix | a | = 2, | B | = - 7, find | a + B | =?
Write a detailed answer

Is there a problem with the title?
If you know the determinant of a and B, you can't determine the determinant of a + B

Add 0.9,7 / 18,1 / 20 to form the proportion {equation}

9 = 9 / 100.9 × 7 / 18 = 7 / 20, so with (7 / 20) / (1 / 20) = 7 ratio: 0.9:7 = 1 / 20:7 / 18 ratio = 9 / 700.9:1 / 20 = 7:7 / 18 ratio = 187 / 18:7 = 1 / 20:0.9 ratio = 1 / 187 / 18:1 / 20 = 7:0.9 ratio = 70 / 90.9 and 1 / 20 group, then (9 / 10 × 1 / 20) / (...)

The harm of land desertification to human beings or the achievements in desert control in China

The harm of land desertification to human beings or the achievements in desert control in China are as follows
Desertification is mainly caused by human (deforestation) (overcultivation) and (overgrazing). At present, the desertification land in China has reached (1.739700 square kilometers), accounting for (18)% of the total land area
In view of this, we have to adjust the strategy of desertification prevention and control, from paying one-sided attention to the development of artificial vegetation to actively developing artificial natural arbor shrub grass composite vegetation; from simply protecting the oasis to actively protecting the entire desert ecosystem including the oasis. Only by reconstructing the desert ecosystem can we fundamentally curb the expansion of desertification, Only by reversing the passive situation of sand control and soil erosion control can we effectively improve the ecological and environmental conditions in Northwest China
.
There are 1.54 million km ^ 2 desertified land in China, accounting for 16% of the total land area, including 1.16 million km ^ 2 desert Gobi, 340000 km ^ 2 desertified land and 40000 km ^ 2 wind desertified land. China's deserts and desertified land are mainly distributed in the area between 37 ° and 42 ° north latitude, with Xinjiang, Gansu, Qinghai, Inner Mongolia, Ningxia, Shaanxi, Shanxi, Hebei and other provinces (regions) being the most serious
Some data show that land desertification is rapidly reducing the territory we can use effectively
The trend of desertification leads to land degradation, destruction of soil structure, loss of soil nutrients, and natural restoration of soil fertility
It will take decades, hundreds, even thousands of years to recover the soil fertility. If the soil fertility is restored by artificial measures, it will take a long time
It is difficult to calculate the amount of investment required
The spring sowing season is from April to May every year,
Often, seeds and fertilizers are blown away, seedlings are uprooted, soil moisture is lost, and seedlings are dried to death or death
Be buried. Some places have to be remedied repeatedly, even missed the farming time
Due to the degradation of grassland caused by desertification, the dominant grass species suitable for livestock consumption are gradually reduced, or even completely lost
The forage became low and sparse, the yield decreased significantly, and the carrying capacity of grassland decreased greatly
Desertification causes the blockage of rivers, reservoirs and canals. The average annual sediment transport of the Yellow River is 1.6 billion tons, of which 1.2 billion tons
About 50 thousand kilometers of irrigation canals are damaged by wind and sand every year
In some areas, desertification has caused damage to railway subgrade, bridges and culverts, and reduced the area of highway subgrade and road
Sand, forcing the road traffic interruption, and even make the road abandoned
Take off and land frequently
Sandstorm activities destroy communication, transmission lines and facilities, and the resulting disasters threaten the safety of residents
According to the monitoring, the main air pollutants in China are micro particles, which are closely related to desertification
Dust pollution of the vast area of people's production and living environment, affecting people's health
According to the survey, 1 / 4 of the rural population in China is poor
Living in the Desertified Area, the per capita agricultural output value is only 34.2% of the national average level, which is the highest in the East
In desertification areas, poverty is increasing and the development gap is widening. Some places have already called out "want to"
To survive is to control desertification

Linlin read a story book. On the first day, she read 1 / 3 more than 2 pages of the book. On the second day, she read the remaining 1 / 2 less than 1 page and left 38 pages. How many pages are there?

Total: 114 pages
Just push back
(38-1) * 2 = 74 pages
[(74 + 2) / 2] * 3 = 114 pages

Given that a and B are rational numbers, m and N represent the integral part and fractional part of 5-7 respectively, and amn + BN2 = 1, then 2A + B = 1___ ．

Because of 2 & lt; 7 & lt; 3, so 2 & lt; 5-7 & lt; 3, so m = 2, n = 5-7-2 = 3-7. Substituting M = 2, n = 3-7 into amn + BN2 = 1, 2 (3-7) a + (3-7) 2B = 1 is reduced to (6a + 16b) - 7 (2a + 6b) = 1, and the result does not contain 7, so 6A + 16b = 1 and 2A + 6B = 0, the solution is a = 1.5, B = - 0.5. So 2A + B = 3-0.5 = 2.5. So the answer is: 2.5

A mathematical problem (passenger cars and freight cars running from a and B at the same time, 60 km / h for passenger cars and 80 km / h for freight cars)
[continued] passenger cars and freight cars depart from a and B at the same time. Passenger cars travel 60 km per hour and freight cars 80 km per hour. The two cars meet 40 km from the midpoint. How many km is the distance between a and B

80-60=20(km)
40×2＝80(km)
80 △ 20 = 4 (hours)
(80+60)×4＝560(km)
A: the distance between AB and ab is 560 km