với mọi n thuộc N thì 10ⁿ-1 = 10....0 - 1 = 9...9 (gồm n chữ số 0, n chữ số 9) luôn chia hết cho 9

Giả sử Linh mua gấp đôi số hàng và phải trả gấp đôi tiền tức là: 8 tập giấy + 6 quyển vở và hết 10800 đồng. Dương mua 7 tập giấy + 6 quyển vở và hết 9900 đồng.

Như vậy hai người mua chênh lệch nhau 1 tập giấy với số tiền là: 10800 - 9900 = 900 ( đồng )

Vậy 900 đồng chính là tiền một tập giấy Giá tiền mua 6 quyển vở là:

9900 - ( 900 x 7 ) = 3600 ( đồng)

Giá tiền 1 quyển vở là:

3600 : 6 = 600 ( đồng )

Đáp số: 900 đồng; 600 đồng

Cách làm hơi lố nhỉ? Xl nhá

Các số có 3 chữ số giống nhau là: 111; 222; 333; 444; 555; 666; 777; 888; 999.

Các số: 111; 222; 333; 444; 555 bị loại

Vì số: 555 - 543 < *** Còn lại ta có: 666 - 543 = 123 777 - 543 = 234 888 - 543 = 345 999 - 543 = 456

Vậy ta có 4 số là: 123; 234; 345; 456.

Đáp số: 123; 234; 345; 456.

Mà hình như đúng rồi mà bn

Quan sát hình phần đất hình chữ nhật đều có chung 1 cạnh ( chiều dài ở hình 1; chiều rộng ở hình 2) nên ta chỉ cần chia cạnh kia thành 2 phần có tỉ số 2 3 là được.

Như vậy hình chữ nhật có chiều rộng là:

20 : ( 2 + 3 ) × 2 = 8 ( m )

chiều rộng AM là :

20 × 2 : ( 2 + 3 ) × 2 = 16 (m )

Vậy cách chia đẹp nhất là chia như hình 2 vì 2 phần đất đều cân đối để xây nhà.

Đáp số: Chia chiều dài thành 2 phần tỉ số là 2/3

After a few minutes of exercise, you move right into your own games. Kia is a group of men kicking around. The soaring volcanic spheres flying from one leg to another are great. This is a group of women are passionate with the jump rope. You alternate who came in, hair flying away.

English not only helps you expand the reach of your communication, impresses with the people around you when you "redeem", but also gives you many other benefits. Do you think of emotions when you are approaching information that everyone is not or not? Then when you make the leap in your career, get away from others an interval? You will achieve all this if you can speak English well.

Access to knowledge What are you interested in? Science, Music, Computers, Health Business or Sports? Today, like the Internet, television, newspapers provide an infinite source of knowledge for your favorite subject, as we live in an age. Chỉ một vấn đề qua tất cả mọi nhất thông tin này. Here are some examples of what you can use if in English.

• Most sites on the net. There are more than 1 billion Web pages in the UK. It is amazing to just learn a language that can exploit most of such knowledge stores.

• Books - about any any fields, anywhere from the world. You can read books by British or American authors, and books are translated from other languages. Whatever type of book you are interested in, you can still find it in English.

Report. Only English newspapers and magazines can be bought anywhere in the world. You do not have to search for newspapers like Time, Newsweek, or the International Herald Tribune.

• Science. Bạn đang mở cửa sổ cho cửa sổ. In 1997, 95% of the articles in the Science Index (Citation Index Science) were written in English. There are about 50% from the words from England and England (Theo garfiled).

• News. Check out the National Grid Network like CNN and BBC. They are faster than the national net. You can see the channels here around the world.

Promote Your Career If you want to find a career in business, technology or science, get up and start learning English now! (If you have a good job, start learning before you lose your job.) Knowing English will help you:

• Display "excellent knowledge of English" on your CV. Likewise working and many more.

Open the Expert Expert English is the language of technology, especially high-tech industries such as computer science, genetics, medicine. If you find a title about your research, you can say you read these posts with English.

• Research for the machine. Read the expert expert without few suchby. Hãy chọn thư mục của bạn!

• Become a world-class business. International Transactions to proceed with English. And những trường này của công ty này hiện tại là khoảng quốc tế. If you want to "get involved", you must know English, contact businesses, attend seminars, read international trade journals and magazines, etc.

• Back to state science. Contact the scientists in other countries, join the conference countries, visit the foreign study center. Learn new information spread through newspapers, magazines.

• Use the computer performance. Most computers use English, so you will understand better and become a better employee.

• Learn new skills for the job. The "Access to Knowledge" section in English helps you learn how.

The feeling of English is not only helpful but also gives you a sense of satisfaction:

• Feeling great. You will never be able to talk to me again.

• You will find it interesting to learn English, if you remember that every hour you spend to learn a time for you is almost complete.

• Use English well because every sentence you write needs to remind you of the success you have achieved.

As such, English helps you become more energetic and happy. Expecting the charm of your friends and acquaintances in the English language will always give you a lot of feeling

Read the passage below and choose one correct answer for each question.

Silk Weaving in the ASEAN Region

For the silk textile lover, the ASEAN region contains a treasure trove of the most beautiful hand-woven fabrics found anywhere in the world. These textiles are surprising in their diversity: from the ikats of Cambodia and Thailand, to the golden songket of Indonesia and Malaysia, to the Philippine pina silk and the Vietnamese silk shantung – each country offers its own century-old weaving traditions to visitors. Weaving at the household and village level is done on large wooden frame looms, often under stilt houses. Intricate Cambodian ikats are world-renowned. It can take up to several days or more to produce one meter of an intricate ikat pattern. Ikat patterns were traditionally passed from generation to generation by memory; prior to the war, more than 200 different patterns were known to be in existence, but it is unclear how many have survived. Artisans Angkor, located in both Siem Reap and Phnom Penh, trains young Cambodians from rural areas in the art of weaving and other Cambodian crafts. In Thailand, the cultivation of silkworms and weaving can be traced back thousands of years. Weaving patterns of  Thailand’s finest weaving, including mudmee, or ikat, are rich anddiverse thanks to the influence of the different ethnic groups, including Khmer and Lao peoples. Mudmee is woven throughout the northeast, with each local community having its own distinct styles and designs, incorporating everything from nagas to elephants and peacocks. While chemical dyes are widely available, some weavers continue to practice traditional dyeing methods passed down through the generations. Viet Nam has become a center for large-scale silk worm and thread production in Southeast Asia, including handloomed silk shantung and jacquards, supplying its neighbors where sericulture is limited or disappeared entirely during the war years. Vietnam has 54 different ethnic groups, each with their own distinct weaving traditions. Among the Black Thai in northwest Vietnam’s Son La province, for example, young girls are expected to learn how to raise silk worms and make natural dyes using indigo.

 Question: What the most distinguished feature of the silk textile in ASEAN?

A. It helps foreign visitors look for treasures of valuable things.

B. You can find different types of silk from anywhere in the world.

C. Each ASEAN country has its own type of silk which is different from any other.

D. It is the diversity of beautiful, traditional hand-woven materials.