Number
SQUARE ROOTS
The square root of a number is the opposite of squaring a number.
e.g.
If the square of 3 is 9 ( which is 3 x 3)
Then the square root of 9 is 3
We can use the sign
to mean square root.
So 9 means ‘the square root of 9’
To find the square root we have to think of a figure, multiplied by itself,
that will give us the number.
e.g.
C.
1)
16 is 4,
because 4 x 4 = 16
9 is 3,
because 3 x 3 = 9
Now have a go at these.
Write down the square roots of these numbers.
25
2)
100
3)
4
4)
36
5) 49
6)
81
7)
64
8)
1
It is not always straightforward to work out the square root of a number.
Sometimes the number is very large, or the square root is not a whole
number.
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Most calculators have a square root sign button. It will have the square root
sign on it.
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Number
D.
Use a calculator to work out the square roots of the
following. Ask a tutor if you are unsure how to use
the square root button.
1)
256
2)
400
3)
900
4)
625
5)
1225
6)
169
7)
225
8)
289
9)
576
10)
961
E.
Now have a go at these. Where you need to, write
your answers to 3 decimal places. The first one is
done for you.
1)
2 = 1.414 to 3 decimal places.
2)
1.44
3)
2.56
4)
9.61
5)
0.25
6)
5
7)
40
8)
20
9)
90
10)
1000
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Check your answers, then discuss with your tutor what you need to
work on next.
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Number
Answers
Square and Square Roots of Numbers
A
B
C
D
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E
1)
16
2)
36
3)
81
4)
1
5)
64
6)
144
7)
225
8)
400
9)
121
10)
625
1)
6.25
2)
12.96
3)
2.25
4)
7.84
5)
0.16
6)
0.36
7)
1.21
8)
0.09
9)
1.96
10)
30.25
1)
5
2)
10
3)
2
4)
6
5)
7
6)
9
7)
8
8)
1
1)
16
2)
20
3)
30
4)
25
5)
35
6)
13
7)
15
8)
17
9)
24
10)
31
2)
1.2
3)
1.6
4)
3.1
5)
0.5
6)
2.236
7)
6.325
8)
4.472
9)
9.487
10)
31.623
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