Online, etc., rookie kneeling for a simple math problem Thank you, seniors, thank you

1.The cycle section is 81

2.**The cycle is the cycle section, and the above question says 81 81 81 cycle, so the cycle section is 81, and the previous one is not a cycle because it did not start the cycle.

1) The cycle section is 81 not 8181, the one with the lowest median number of all cycles.

2) The cycle of the knot is 81 not 18 (18 18 18), the number of the first is not the last.

That's probably it, don't understand and ask me again :), must - -

.The cycle section is 81

The cycle section depends on where the decimal starts the cycle, and when there are only these few numbers in the cycle, these numbers are the cycle section.

For example, the cycle section is 69

In the number cycle section, you should pay attention to where the number starts to loop, and do not count the numbers that have no loop in front of you.

For example, the cycle section is 426, not 7426

2 Number from the first place in the start cycle Cycle sections should be as short as possible (so 81 instead of 8181 or 818181).

3 I almost forgot, you look at the book (the main thing is that it's too simple, it doesn't seem to need to pay attention to anything).

I've almost forgotten, you can read the book.

Question 3: Solve the grinding and answer the spring and search the picture below.

1.For a piece of wire, the use of the remaining two-thirds, the ratio of the used to the rest is [2:3], the use of a fraction of the total length [2 5], the rest of the total length [3 5].

2.A section of wire, used 20 meters, 30 meters left, used [2 5] and left [3 5].

3.A pile of coal weighs 27 tons, and a certain factory uses a quarter of the total amount in 3 days, so calculate the total number of [5 7] used in 5 days, and the total amount of [135 7] is about equal to tons in five days.

4.Number B is seven-eighths of the number A, number A: number B = [8:7], number B is 2, and number A is [16 7].

5.A number increases by a third of its sum to 80, what is this number? 【Equation Answer】 80 (1+1 3)=60

6.The railways between A and B are 464 kilometers long, and a passenger car and a freight train depart from the two places at the same time, running in opposite directions, meeting in 16 hours out of a fifth. Passenger cars travel 76 kilometers per hour, how many kilometers does a truck travel per hour? [Equation].

464-76*(16/5)]/(16/5)=464/(16/5)-76=697.Master Wang weaved two-fifths of a meter-long blanket in two-thirds of an hour, and Master Li knitted one-fifth more than Master Wang in the same amount of time. How many hours does it take for Master Wang to weave a 1-meter-long blanket?

What about Master Li? 【Equation】 Master Wang: (2 5) (2 3)=3 5; Master Li:

8.In poverty-stricken areas, students in two classes of the sixth grade of a primary school donated a total of 125 books. It is known that the number of books donated by Class 6 is two-thirds of that of Class 6, how many books are sent by Class 6 and Class 6?

Equation: Class 125 (2 3+1)=75;Class 75 * (2 3) = 50

Oh, I hope it can help you...

1 。2:3, fifths.

Two, three-fifths.

2 。Fifth.

Two, three-fifths.

3 。Five-twelve, 27 Five-twelve.

4 。7:8, seven-quarters.

5 。80 (1+3)=60

6 。464 Sixteen fifths—76=145—76=697. 2/5 2/3 = 3/5, 3/5 + 1/5 = 4/58.

Class 2: 125 (1 + two-thirds Class: 125-75=50.)

1.2:3 2/5 3/5 2Two out of five Three out of five.

3.Five-twelve, 27 Five-twelve.

4.7:8, seven-quarters.

5.80 (1+3)=60

The radius of the big wheel is meters, and the square of the radius corresponds to a ratio of 1:9, so the money also corresponds to a ratio of 100:900The answer is 900 yuan.

A typical circumference ratio problem should be $300.

Answer: an=a(n-1) (3a(n-1)+1) take the reciprocal on both sides.

1/an=3+1/a(n-1)

1/an-1/a(n-1)=3

is a series of equal differences, the first term is 1, and the tolerance is 3

1/an=1+3(n-1)=3n-2

an=1/(3n-2)

bn=1/[(3n-2)(3n+1)]∴bn=1/[(3n-2)(3n+1)]=(1/3)[1/(3n-1)-1/(3n+1)]

sn=(1/3)*[1/1-1/4+1/4-1/7+..1/(3n-1)-1/(3n+1)]

1/3)*[1-1/(3n+1)]

1/3)[3n/(3n+1)]

n/(3n+1)

Such a basic question? It's OK to do it the other way around.

1、[54÷(9-3)]-54÷9)

3 (cm)2, (=2x5 2 square centimeters).

43 (mm).

4. Number C is: 360 (3x2+2+1)=40 Number B is: 40x2=80

The number of A is: 80x3=240

1.Height = 54 2 9 = 12 cm.

Height increase = 54 2 (12-3) - 9 = 3 cm2Height = meters.

Original area = square meters.

3.Xiaoliang speed = (860-300) 7-37 = 43 meters min 4C = 360 (1 + 2 + 2 3) = 40

B = 40 2 = 80

A = 80 3 = 240

50*[b+a-(b-a)]+b-a)=b+99a or: [a+(b-a) 2]+98a+[a+(b-a) 2]=b+99a

The latter method may be more intuitive, and the order of addition is the arrangement of the rings after straightening.

Detailed explanations and answers to the exam papers in mathematics I hope that those in the know will reply as soon as possible Thank you for your urgent use 8(1) The radius in the question is known, and the central angle of the circle is 120°, so it is not difficult to find the length of each fan-shaped arc2) The radius of the sector D1 is 1cm

It's more obvious to draw a picture.

When the two ring sleeves are straightened together, the length is (b - a) 2 = 2b - 2a a joint, and the effect on the total "length" is reduced by 2a

Then 100 rings, if they are set into a chain (a rope), have 99 joints.

The total length is 100b - 99 2a = 100b - 198a If you put it into a chain ring (one loop), there are 10 joints.

The total length is 100b - 100 2a = 100b - 200a

[a×π－b－a）]×1/2×100

is pi, first find the circumference of the inner circle, then subtract the thickness of the ring, after the ring is straightened, only half of the inner circumference remains, and then multiply by 100.