Reading 3

1
Chapter 4 Reading 3 P49
Shenyang No.143 Middle School Chen Hua
2
calculating machines
Read answer

• What are the three calculating machines?
• Why do people still use abacuses?
• What is an abacus made up of?
• What do the beads mean on the abacus?
• What can an electronic calculator do?
• What do you think of computers as calculating
  machines? Give an example.

An abacus, an electronic calculator and a
computer.
Because they are so fast and accurate.
Beads and wires.
They represent ones, tens hundreds and thousands,
starting fron the bottom wire.
It can add, subtract, multiply, divide
and calculate percentages and square roots.
Very powerful.
3
One of the first calculating machines was an
abacus. Abacuses are so fast and accurate that
people still use them today. On the abacus in
the picture, the beads on the wires represent
ones, tens, hundreds and thousands, starting
from the bottom wire.
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The picture on the right shows a modern
electronic calculator. It can add, subtract,
multiply and divide. It can also calculate
percentages and square roots.
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5
This picture shows a computer. Computers are
very powerful calculating machines. In a flash, a
computer can do a calculation that you could not
do in your whole lifetime.
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Who can solve the problem?
Shakuntala Devi
an Indian lady
x23
91674867692003915809866092758538016248310668014430
86224071265164279346570408670965932792057674808067
90022783016354924852380335745316935111903596577547
34007568168830562082101612913284554680578015880677
1
x
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7
Which is more powerful?
a human brain
Brain against computer
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Brain against computer

• What do we call the brain?
• What brain does Shakuntala have?
• How fast can she calculate?
• How long did it take her to find the answer?
• How long didit take the computer to do it?
• What did people to to the computer before it
  began calculating?
• Did anyone program Shakuntala?
• Is a human brain a more powerful calculator?

Listen, read answer
A living computer.
An amazing brain.
Like lightning.
Fifty seconds.
A mimute.
People had to program it with instructions.
No.
Yes.
9
.

• Ancient numbers in tens ./ Ancient people wrote
  numbers in different ways, but counted them in
  the same way --- in tens.
• Indians invented and developed the system of
  numbers from 1 to 9 and 0.
• Something about three calculating machines.
• A human brain is more powerful than a computer.

Main ideas for each part
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• Brain against computer
• Some people called brain a living computer. Is
  a human brain a more powerful calculator than a
  computer? The following story may give an answer.
• Shakuntala is a lady from India with an
  amazing brain. She can calculate like lightning.
  In America, Shakuntala and a computer were given
  this problem to solve.

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• Shakuntalas brain took fifty seconds to find
  the answer.The computer took a minute. However,
  before the computer could begin calculating,
  someone had to program it with instructions, and
  that took many hours. No one had to program
  Shakuntala!
• Use your own living computer to solve the
  problem above, if it is not powerful enough, you
  will find the answer on Page 59.

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HOMEWORK

• Copy new words and key points.
• Repeat the part of
• brain against computer.