Chapter 25 Indices, standard form and surds
Example 5
Write as an ordinary number
a
3 10
b
1.5 10
6
3
___
3
___
1.5
a
3 10
6
b
1.5 10
3
10
6
10
3
_______
____
3
15
1 000 000
1000
0.000 003
0.0015
Exercise 25C
B
Write these numbers in standard form.
1
a
0.005
b
0.04
c
0.000 007
d
0.9
e
0.0008
Write these as ordinary numbers.
2
6 10
8 10
5 10
3 10
1 10
a
b
c
d
e
5
2
7
1
8
Write these numbers in standard form.
3
a
0.0047
b
0.987
c
0.000 803 4
d
0.000 15
e
0.601
Write these as ordinary numbers.
4
8.43 10
5
2.01 10
2
4.2 10
7
7.854 10
1
9.4 10
4
a
b
c
d
e
Write these numbers in standard form.
5
a
457 000
b
0.0023
c
0.0003
d
2 356 000
e
0.782
f
89 000
g
200
h
0.005 26
i
6034
j
0.000 008 73
Write these as ordinary numbers.
6
3
7
8
4
6
a
4.12 10
b
3 10
c
2.065 10
d
4 10
e
3.27
10
2
5
1
7
1
f
7.5 10
g
1.5623 10
h
5.12 10
i
2.7
10
j
6.12 10
1 micron is 0.000 001 of a metre. Write down the size of a micron, in metres, in standard form.
7
A particle of sand has a diameter of 0.0625 mm. Write this number in standard form.
8
Example 6
Write in standard form
a
40 10
2
b
0.008 10
2
Examiner’s Tip
Method 1
Write 40 in standard form.
a
40 10
2
4 10
1
10
2
The power of 10 tells you how
a
m
a
n
a
m
n
Use the rule
.
4 10
12
many 0s there are.
4 10
3
10
2
100
2 zeros
10
0.01 2 zeros
2
b
0.008 10
–2
8 10
10
3
2
Write 0.008 in standard form.
8 10
3 2
a
m
a
n
a
m
n
Use
.
8 10
5
614