Chapter 4《The world of numbers》reaging课件1(23页

C 5/8 D÷ E=
F 13 45
G 8 210 H 90° I× J 0.82
K 45% L－
Numbers, Everyone's Language
245×619÷35－891＋521=?
Calculating Machine
an abacus wires
• one of the first calculating machines
• They represent ____o_n_e_s_,_t_e_n_s, __h_u_n_d_r_e_d_s_,_t_h_o_u_s_a_n_d_s__a_n_d__s_o on.
• She can calculate like lightning.
How long can a computer do a calculation?
• In a flash.
How long did the computer take to solve the difficult problem?
A: What else can it do?
B: It can calculatepe_r_c_e_n_t_a_g_e_s__ and s_q_u__a_re__ro__o_ts_.
Calculating Machine
an electronic calculator
A: What can ___________ do?
• A .
What should people do to make computers calculate?
• People have to__p_r_o_g_ra_m__t_h_e_m___ __w_i_th__in_s_tr_u_c_ti_o_n_s____.
What do the beads on the wires represent?
Chapter 4
reading
Language points
Numbers
practice
Calculating machines
A What do you know about…?
1 a decimal numbers
A+
2 a pair of odd numbers
B0
3 a fraction 4 zero 5 add;plus 6 subtract;minus 7 mutiply; times 8 divide 9 a number showing degrees 10 a percentage 11 a pair of even numbers 12 equals
Calculating Machine
a computer
• powerful • a flash • in your whole lifetime
A _c_o_m__p_u__teisr a very ______p_owcaelcrufluatling machine. In ______, it can dao aflacaslhculation that you could not do
_____________
in your whole
_l_if_e_t_im__e.
n. abacus
bead
wire percentage square root
calculator
calculation
v. represent
add
subtract multiply divide
calculate
program
a. accurate
electronic
powerful amazing
Read the text
Competition
Answer the questions
1
8
2
7
3
6 54
Why do people still use abacuses today?
• Because they are accurate and fast.
B: It ____________________. A: What else can it do? B: It ____________________.
Calculating Machine
a computer
• powerful • a flash • in your whole
lifetime
add subtract multiply
divide
calculate percentage square root
Calculating Machine
an electronic calculator
A: What can an electronic calculator do?
B: It can __a_d_d_____, _s_u_b__tr_a_c_t_, __m_u_l_ti_p_l_y_ and __d_i_v_id_e___.
What can an electronic calculator do?
• It can add, subtract, multiply and divide. It can also calculate percentages and square roots.
How fast can Shakuntala Devi calculate?
• accurate and fast
• represent
— thousands — hundreds — tens — ones
5,7 2 4
beads
Calculating Machine
an abacus
Calculating Machine
an electronic calculator