Primary 6 math concepts, the more the merrier!! 5

The fraction is multiplied by an integer, and the numerator of the fraction and the product of the integer multiplied are used as the numerator, and the denominator remains unchanged.

The integer is multiplied by the fraction, and the product of the numerator of the integer and the fraction is used as the numerator, and the denominator remains unchanged.

Fractions are multiplied by fractions, and the product of the multiplication of the numerators is used as the numerator, and the product of the multiplication of the denominator is the denominator.

To multiply three numbers, for the sake of simplicity, you can first divide the numerator and denominator of all fractions, and then multiply the numerator and denominator after the reduction.

The product of 1 is the reciprocal of two numbers with each other.

To find the reciprocal of a number (except 0), just switch the numerator and denominator of the number.

The meaning of fraction division is the same as that of the certificate, that is, knowing the product of two factors and one of the factors, and finding the operation of the other factor.

The fraction divided by an integer (except 0) is equal to the fraction multiplied by the reciprocal of this integer.

A number that indicates that one number is a percentage of another is called a percentage. Percentages are also called percentages or percentages.

To convert decimals to percentages, move the decimal point two places to the right and add a percent sign after it (if the number of digits is not enough, use 0 to make up).

To convert a percentage to a decimal place, remove the percent sign and move the decimal point two places to the left.

To convert the fraction into a percentage, usually the fraction is converted into a decimal place (when there is an inexhaustible division or a large number of decimal places, three decimal places are generally retained), and then the decimal is converted into a percentage.

To convert a percentage into a fraction, first rewrite the fraction as a fraction with a denominator of 100, and then divide the fraction into the simplest fraction.

When drawing a circle, a fixed point is called the center of the circle, and the center of the circle is usually represented by the letter o; The line segment from the center of the circle to any point on the circle is called the radius, and the radius is usually represented by the letter r; The segment of the line that passes through the center of the circle and is on the circle at both ends is called the diameter, and the diameter is usually denoted by the letter d.

If a flat figure is folded in half along a straight line, and the two sides of the figure can coincide exactly, the figure is the axis of symmetry figure. The straight line where the crease is located is called the axis of symmetry.

The length of the curve that encloses the circle is the circumference of the circle.

For circles of different sizes, the circumference is always a little more than 3 times the diameter. This multiple is a fixed number, which we call pi, and is represented by letters (pronounced pāi).

Germination rate = number of germinated seeds Total number of test seeds * 100%.

Organize the concepts in the book and review them!

Don't be so lazy.

Children!

Multiply in parentheses. ，。

Glad to serve you, take it!!

1.Solution: 500 grams = kilograms.

There are 112 grains per kilogram, that is, there are 112 * 2 = 224 (grains) per kilogram, so 3 kilograms of longan have 224 * 3 = 672 (grains) Answer: 3 kilograms of such longan have about 672 grains.

2.Solution: 15% price reduction, that is, 85% of the original price for sales, according to the title, get 10,000 yuan).

A: Now this car costs 10,000 yuan per car.

3.Solution: The whole school donated a total of x yuan.

Grade 5 donation: 20% x

Donation amount for 6th grade: 25% x

According to the title, there is.

25%x-20%x=200

x=4000

A: The whole school donated a total of 4,000 yuan.

4.Solution: Let the original tree be x, because after removing the decimal point from a one-digit decimal point, it will be 10 times larger than the original decimal place, that is, the current decimal is 10x, according to the title, there is.

10x-x=

9x=x=A: So the original decimal is.

5.Solution: Two identical dice show a number of 6*6=36 with a probability greater than 4 in the following cases: 2,3 2,4 2,5 2,63,2 3,3 3,4 3,5 3,6

4,1 4,2 4,3 4,4 4,5 4,65,1 5,2 5,3 5,4 5,5 5,66,1 6,2 6,3 6,4 6,5 6,6 There are 27 cases, so the probability of the number on the two faces facing up and greater than 4 is 27 36 = 3 4

1. (3000 500) * 112 = 672 grains 2, 10,000 yuan After the price reduction, it is 85%** (1 4-20%) = 4000 yuan The sixth grade donations are more than five years, accounting for 1 4-20% = 5% of the school's donation

4. After removing the decimal point, the number is expanded by 10 times, and the subtraction is 9 times the original number.

(1 6*1 6+2 6*1 6+2 6*1 6+1 6*1 6)=30 36=5 6 Less than or equal to 4 means that both are 1, two 2, one 1, one 2, one 1, one 3

Do you want a process.

Two barrels of oil A and B have a total of 80 kilograms, and 20% is poured out from barrel A and put into barrel B, and the two barrels weigh the same. How many kilograms does the original bucket weigh?

Let the original barrel B weigh x kilograms, then A was originally (80-x) kilograms, and now the two barrels of oil weigh the same, so both barrels of oil are 40 kilograms, then there is:

80-x）×（1-20%）=40

Solution: x=30

A: It turns out that the second barrel weighs 30 kilograms.

Solution: There are x pages in this book.

Seen on the first day: 10%x

The next day I watched: 24

The number of pages left is: x-(10%x+24).

The ratio of the number of pages read to those not read is 1:3, and the column equation: (10%x+24) [x-(10%x+24)]=1 3

x=80

The first question is (80-x)*20%+x=(80-x)*(1-20%)(x represents the weight of B barrel of oil) and finally x is equal to 30

The second question is) (24+10%*x): [x-(24+10%*x)] =1:3 (x

Indicates the number of pages of the book) The last x is equal to 160

Equation 1x-20%x=y+20%x....Equation 2 is solved by equation 1 and equation 2: x = 50 kg, y = 30 kg 2(10%x+24): [x-(10%x+24)]=1:3 solution x=160 (page).

1. Solution: Let the B oil drum be x kg, and the oil oil drum 80-x kg (80-x) 80 = x + (80-x) 20 x = 50 kg.

2. Let the book be x pages (10% x + 24) (90 -24) = 1 3x = 160 pages.

kg = 6 pcs 500 grams.

112 6 = 672 (grains).

2. 10,000 yuan) 3. The whole school will donate a total of Y yuan.

1/4y-20％y=200

y=4000

4. Let the original decimal be y

10y-y=y=

You still have to do your homework and think about it yourself, kid, you're only in the 6th grade.

The first question. ：1/8=x:10

1 8x=x=x=20 Question 2.

105:42=9：x

105x=42*9

*3000/500=672

The probability of greater than 4 is: 2 6 = 1 3

The probability that both of them are greater than 4 is 1 3*1 3=1 9 Answerer: 137100899 |Level 2 | 2011-5-6 16:08 |Report.

1. If there are x grains of longan per gram, 500 112 = 3000 x, then x = 672 grains.

2. 10,000 yuan. 3. If the whole school donates x yuan, 1 4 * x - 20% * x = 200, then x = 4000 yuan.

4. Let the original decimal be x, 10x-x= , then x=

2,3,200 [(1 4)-20%] = 4,000 yuan.

4. Let this number be x, then 10x-x=, x=

5. Calculate the probability of the sum of the two dice facing up to 4, and the first number with the dice facing up may be: 1 or 2 or 3 or 4 or 5 or 6

The second dice may also be numbered upwards: 1 or 2 or 3 or 4 or 5 or 6

Therefore, the sum of the two faces 4 is possible, 1+1, 1+2, 1+3, 2+1, 2+2, 3+1, so there are 6*2=12 cases, and the sum of the two bones facing up has a total of a(62)=30 possible situations.

So, the probability of the sum of the two faces 4 is 12 30=

3 kg = 3000 grams, 3000 divided by 500 = 6 (pieces), 112x6 = 672 (grains).

10,000 yuan) 10,000 yuan

Solution: The whole school donated a total of x yuan.

1/4x—20%x=200

25%—20%)x=200

5%x =200

x=4000

Solution: Let the original decimal be x.

10x—x=

9x =x=Zheng has (1+6,1+5,2+6,2+5,2+4, 2+3,3+6, 3+5, 3+4, 3+3

4+6， 4+5， 4+4, 5+6， 5+5， 6+6.There are 16 of them.

There are 5 (1+1, 1+2, 1+3, 1+4, 2+2) after Zheng is younger.

Then: 16 + 5 = 21 (pcs).

So the probability of the sum of the two faces 4 is: 16 21

*3000/500=672

The probability of greater than 4 is: 2 6 = 1 3

The probability that both of them are greater than 4 is 1 3 * 1 3 = 1 9

1,(3000/500)*112=672

2,3,200 [(1 4)-20%]=4000 yuan4, let this number be x, then 10x-x=,x=

5, first calculate the probability of the sum of the two dice facing the top 4, the first number of the dice facing up may be: 1 or 2 or 3 or 4 or 5 or 6 The number of the second dice facing up may also be: 1 or 2 or 3 or 4 or 5 or 6 So, the possible cases of the sum of the two sides 4 are, 1 + 1, 1 + 2, 1 + 3 , 2 + 1, 2 + 2, 3 + 1 so there are a total of 6 * 2 = 12 cases, and the sum of the two bones facing up has a total of a (62) = 30 possible situations So, the sum of the two faces The probability of 4 is 12 30 = so the sum of the two faces is 4 likely.

1. If there are x grains of longan per gram, 500 112 = 3000 x, then x = 672 grains.

2. 10,000 yuan. 3. If the whole school donates x yuan, 1 4 * x - 20% * x = 200, then x = 4000 yuan 4, let the original decimal be x, 10x-x = , then x 21

3 kg = 3000 grams, 3000 divided by 500 = 6 (pieces), 112x6 = 672 (grains).

10,000 yuan) 10,000 yuan

Solution: The whole school donated a total of x yuan.

1/4x—20%x=200

25%—20%)x=200

5%x =200

x=4000

Solution: Let the original decimal be x.

10x—x=

9x =x=Zheng has (1+6,1+5,2+6,2+5,2+4, 2+3,3+6, 3+5, 3+4, 3+3

4+6， 4+5， 4+4, 5+6， 5+5， 6+6.There are 16 of them.

There are 5 (1+1, 1+2, 1+3, 1+4, 2+2) after Zheng is younger.

Then: 16 + 5 = 21 (pcs).

So the probability of the sum of the two faces 4 is: 16 21