Angka 9 Yang Ajaib

• Keajaiban Yang Pertama : Semua angka yang dikalikan dengan angka 9, 99, 999, 9999 dan seterusnya dapat kita hitung menggunakan cara selain perkalian bersusun.

Contoh 1 :
Coba anda hitung hasil dari 1756 x 9 = …

Cara menghitungnya adalah sebagai berikut :
Karena 9 = 10 – 1

Maka 1756 x 9    = 1756 (10 – 1)                                   = 1756(10) – 1756(1)
= 17560 - 1756
= 15804

PANGLIMA BESAR SOEDIRMAN

INTERNATIONAL ISLAMIC JUNIOR HIGH SCHOOL (PBS-IIJHS)

Jl. Raya Bogor Km. 24 Cijantung East Jakarta - INDONESIA

BRIEF PROFILE

1.  1. one of the caretaker of Excellent Colleague in Jakarta    since 1995 until now from 48 public/private Junior High School
2.  2. one of eleven pioneer school in Accelerated Learning Program (Acceleration) in Indonesia, according to the Decree of General Director of Primary and Secondary Education No 217/kep./MN/2000 on July 17^th, 2000. It was stated in the Decree of General Directory of Primary and Secondary Department of National Education that 56 schools of primary school, junior high school and senior high school in 26 provinces of Indonesia

MATH CORNER

By : Mas Tanto

 Pada edisi kali ini Math Corner tidak menampilkan keajaiban-keajaiban seperti pada edisi sebelumnya, akan tetapi menghadirkan permainan matematika yang bisa membantu mengasah otak kita.

Untuk mendampingi liburan kalian, yang barang kali ada yang ingin jalan-jalan, atau sekedar refresing nginep di Puncak Bogor, atau kegiatan apa saja yang kalian kerjakan pada liburan semester ini, teka-teki ini bisa kalian bawa dan bahkan keluarga, sanak famili dan handai taulan kalian bisa nimbrung untuk bersama-sama memecahkannya.

1. Susunlah angka 1 sampai dengan 8 pada gambar di bawah ini sedemikian sehingga angka yang berurutan tidak bersisihan atau berada pada persegi-persegi yang sudutnya bertemu.

1. Susun delapan lingkaran seperti tampak pada gambar di bawah !

Pindahkan dua yang berdekatan untuk memperoleh susunan seperti gambar berikut !

1. Gambarlah sebuah persegi, tandai delapan potong kertas dengan ukuran yang sesuai dan susunlah mereka seperti terlihat pada gambar di bawah di sebelah kiri. Dengan menggeser sekali setiap kertas ke persegi yang kosong, susun kertas-kertas bernomor berikut sehingga susunannya menjadi seperti pada persegi di sebelah kanan.

HISTORY OF MATH

Mathematics started with counting. In about the 2000 BC’s, the Babylonians developed some mathematical ideas.

Number problems like the Pythagorean triples (discovered by Pythagoras and the Pythagoreans, his students) were studied from 1700 BC. Linear equations were studied to solve problems, as well as quadratic equations. These led to a kind of numerical algebra.

The Greeks studied similar figures, volume and area (geometry problems). Values were also determined for p .

The Babylonian’s mathematics passed on to the Greeks. From 450 BC on the Greeks studied and improved many kinds of mathematics.

The ancient Greeks discovered conic sections (circular shapes formed when cutting a cone at different angles). They also made many discoveries in astronomy and trigonometry.

While the Greeks’ greatest mathematical discoveries were occurring between 300 BC and 200 BC, mathematics was also making progress in Islamic countries, such as Iran, Syria, and India. These mathematics were not as highly developed then the Greeks. The Islamic mathematics, however, preserved the works of the Greeks. They were brought back to Europe in the eighteenth century.

Major work in mathematics in Europe began in about the sixteenth century, with the mathematician Girolamo Cardan and some others, such as Tartaglia, Ferrari, and Pacioli. They reformed what people thought the universe and mathematics were like.

During the seventeenth century, mathematicians made more and more progress towards calculus and added some algebraic methods to geometry.

The development toward calculus continued with the great mathematicians Pierre de Fermat. Together, with Blaise Pascal, they began the mathematical theory of probability. However, calculus evolved in the seventeenth century.

Newton, Sir Isaac, discovered the branch of mathematics called calculus. He called it fluxions, which meant changing. His new discoveries contained an interaction between physics, astronomy, and mathematics. His theories on light and gravitation took us to the eighteenth century.

Two branches of mathematics were invented in the eighteenth century, the calculus of variations and number theory, which had begun with Fermat.

Resource : ThInkquest.org

MATH AT HOME

How much does it cost to light your house? This is a very practical use of math. The equation to calculate the cost of lighting is:

C = (W/1,000) ´ R ´ N

Where

C = cost of lighting the bulb

W = label on the bulb in watts (W)

R = rate of electricity that shows on your electric bill $ / KWH

N = number of hours of usage

Note: 1/1,000 means to convert watts to kilowatts

Bill’s mother bought a 100-W lightbulb for Bill’s room. He used the light about 4 hours per night. The electric rate in the city he lives in is $0.1 KWH. How much does his mother pay for the lighting bills for his room per month (30 days)?

C = (100/1,000) ´ ($0.1) ´ (4 ´ 30)

= $1.2

Bill’s mother must pay $1.20 for the light bill every month.

Bill's mother changed the lamp to a more efficient fluorescent light that shows 25-W on the label. By how much will the lighting bill change in a 30-day month?

Estimate the answer:

Less than 25¢
Between 25¢ and $1.00
Over $1.00

Resource : ThInkquest.org