I m asking you a 6th grade math problem, a 6th grade math problem

Solution: The diameter length of the cylinder is increased to 20 cm, and the thickness of the paper on one side is (20-10) 2=5 cm

The thickness of the paper is 5 times.

The minimum diameter of the paper tube is 10cm, the maximum diameter is 20cm, and the average diameter is (10+20) 2=15cm

So the total length of the paper is 15*

A: The total length of such a roll of web is meters.

From the side of the web, you can use the area of the ring to calculate The paper can be straightened in your mind, so that the side of the web is pulled into a rectangle of centimeters wide, and the area of this rectangle is the area of the ring, and then just divide the area of the rectangle to find the length of the paper

Solution: the side area of the web: , square centimeters);

The length of the web: cm);

A: The total length of this roll of paper is 11,775 cm.

Solution: the side area of the web: , square centimeters);

The length of the web: cm);

A: The total length of this roll of paper is 11,775 cm.

,, square centimeters);

The length of the web: cm);

This recorder is worth $ x.

1 year remuneration RMB 660 + a tape recorder.

1 month's remuneration = 55 + 1 12x

7 months remuneration = 7 (55 + 1 12x) = 150 + xx = 564

Solution: 12-7=5

660-150 = 510 (yuan).

510 5 = 105 (yuan).

105 12 = 1260 (yuan).

1260-660 = 600 (yuan).

A: The price of this recorder is 600 yuan.

Therefore, the original question can be replaced with the form on the right, and the result is 1 1-1 2+1 2-1 3+1 3-1 4+...1/99-1/100

...Detailed justification. Nope. This is derived. 1/n(n+1)=1/n-1/n+1

It's easy to ask, and it can be solved like this.

High is 12 It can also be solved like this: (32,24)=8

24÷3=8(cm) 4×8=32

The diameter of the bottom surface is 8 cm 3 8 = 24

The diameter of the bottom surface is 8 cm, and the height is 12 cm.

Solution: Find the greatest common divisor of 32 and 24 as 8

Length = 4 * 8 = 32

Width = 3 * 8 = 24

The bottom surface of the peanut milk bottle is 8 cm in diameter and 12 cm in height.

Answer: The bottom diameter of peanut milk is the common factor of 32 and 24;

Then the common factors of 32 and 24 are 1, 2, 3, 8;

Check it, only when the bottom diameter is 8 cm, the length can be 4, the width can be 3 rows, a total of 12, so the bottom diameter is 8 cm, and the height is 12 cm.

There are several ways to calculate the diameter without high invariance.

The simplest is length 32 - width 24 = 8, so it can be said that it is arranged by 3 times 4. The diameter is 8.

Pay more attention to discovering patterns.

Decompose Prime Factors:

The 12 milk bottles are placed on the bottom surface with 4 lengths and 3 widths.

Diameter of milk bottle: 32 4 = 8 (cm) or 24 3 = 8 (cm).

Because the box is full, the height of the milk bottle is 8cm.

The common divisor of length and width is and so on, one of which is the base diameter. 32 Base diameter multiplied by 24 Base diameter = 12

Tried base diameter = 8

If it's just full, the height is 12

If the radius is increased by 1 6, that is, the original 1 + 1 6 = 7 6, then the area is the original 7 6 * 7 6 = 49 36

So, the original area = 78 (49 36-1) = 216 square centimeters.

Let the original radius r, the original circle area = r

7r/6)²-r²=78

49/36-1)πr²=78

r²=78*36/13

r²=216（cm²）

Answer: The original circle area is 216cm

Let the radius be r, then.

49/36r^2-πr^2=78

13/36*πr^2=78

r^2=216

The area of the circle is 216cm