Page 9 - 新思维数学活动用书9 样章

1 Number and calculation

Practice

5 Write these numbers in standard form.
a 0.000 03 b 0.000 000 666
c 0.000 050 5 d 0.000 000 000 48

6 These numbers are in standard form. Write each number in full.
a 1.5 × 10 −3 b 1.234 × 10 −5
c 7.9 × 10 −8 d 9.003 × 10 −4
7 Write these numbers in full.

a 8 × 10 −6 b 4.82 × 10 −7
c 6.1 × 10 −5 d 7.007 × 10 −8
8 The wavelength of visible light is between 0.000 000 4 m and 0.000 000 8 m.
Write each of these numbers in standard form.

9 Look at these five numbers.
A = 9.8 × 10 B = 1.2 × 10 C = 3.05 × 10 −7
−6
−7
D = 4.81 × 10 E = 5.17 × 10 −7
−6
Write the numbers in order of size, smallest first.

Challenge

10 The mass of Earth is 5.98 × 10 kg.
24
a When you write this mass in full, how many zeros does it have?
1
b The mass of Mars is approximately of the mass of Earth. Write the mass of Mars in
10
standard form.
11 a Copy and complete this sentence:
6.2 × 10 is times larger than 6.2 × 10 .
6
7
b How many times larger than 8.5 × 10 is 8.5 × 10 ?
−3
3
12 These numbers are not in standard form. Write each number in standard form.
a 45 × 10 6 b 28 × 10 8
c 300× 10 4 d 995 × 10 7

13 Write each of these numbers in standard form.
a 43 × 10 −5 b 125 × 10 −8
c 0.7 × 10 −5 d 0.08 × 10 −7

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