Page 14 - 新思维数学学生用书9 样章

1.2 Standard form

Exercise 1.2

1 Write these numbers in standard form.
a 300 000 b 320 000
c 328 000 d 328 710

2 Write these numbers in standard form.
a 63 000 000 b 488 000 000
c 3 040 000 d 520 000 000 000
3 These numbers are in standard form. Write each number in full.
a 5.4 × 10 3 b 1.41 × 10 6

c 2.337 × 10 10 d 8.725 × 10 7
4 Here are the approximate distances of some planets from the Sun.
Write each distance in standard form.

Planet Mercury Mars Uranus
Distance (km) 57 900 000 227 900 000 2 870 000 000
5 Here are the areas of four countries.

Country China Indonesia Russia Kazakhstan
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Area (km ) 9.6 × 10 6 1.9 × 10 6 1.7 × 10 7 2.7 × 10 6
a Which country has the largest area?

b Which country has the smallest area?
c Copy and complete this sentence with a whole number:
The largest country is approximately … times larger than the smallest country.
6 Write these numbers in standard form.

a 0.000 007 b 0.000 812
c 0.000 066 91 d 0.000 000 205
7 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
8 The mass of an electron is 9.11 × 10 kg. This is 0.000…911 kg.
−31
a How many zeros are there between the decimal point and the 9?
b Work out the mass of 1 million electrons.

Give the answer in kilograms in standard form.

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