year 8 maths

228 Chapter 4 Fractions, decimals, percentages and financial mathematics
16 Two students give the following answers in a short test on rounding. Both students have one
particular misunderstanding. Study their answers carefully and write a comment to help correct
each student’s misunderstanding.
Rounding question Student A Student B
0.543 (2) 0.54 ✓ 0.50 ✗
6.7215 (3) 6.721 ✗ 6.722 ✓
5.493 (1) 5.5 ✓ 5.5 ✓
8.2143 (3) 8.214 ✓ 8.210 ✗
11.54582 (2) 11.54 ✗ 11.55 ✓
ENRICHMENT
– –
17
Will it terminate or recur?
17 Can you find a way of determining if a fraction will result in a terminating (T) decimal or a
recurring (R) decimal?
a Predict the type of decimal answer for the following fractions, and then convert them to see if
you are correct.
i
iii
v
1
8
1
14
1
20
A key to recognising whether a fraction will result in a terminating or recurring decimal lies in the
factors of the denominator.
b Write down the factors of the denominators listed above.
c From your observations, write down a rule that assists the recognition of when a particular
fraction will result in a terminating or recurring decimal.
d Without evaluating, state whether the following fractions will result in terminating or recurring
decimals.
1
1
i
ii
16
9
1
1
iii
iv
42
50
1
1
v
vi
vii
75
1
200
ii
iv
vi
1
12
1
15
1
60
99
viii
1
625
Cambridge Maths NSW
Stage 4 Year 8 Second edition
ISBN 978-1-108-46627-1 © Palmer et al. 2018
Cambridge University Press
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