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Decimals
Mark Scheme
Level
Subject
Exam Board
Topic
Sub Topic
Booklet
IGCSE
Maths
Edexcel
Number and Algebra
Decimals
Mark Scheme
17 minutes
Time Allowed:
Score:
/14
Percentage:
/100
Grade Boundaries:
A*
A
B
C
D
E
U
>85%
75%
70%
60%
55%
50%
<50%
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Question
1.
Working
Mark
Answer
x = 0.396396…
1000x = 396.396....
999x = 396
M1
2
A1 must reach
111
2.
Notes
See at least 3 sevens or recurring symbol. Condone omission of x.
M1
Accept 10x = 1.777.. and 100x= 17.77..
A1
Must be integers in numerator and denominator
but not 8 & 45
N.B for 0.1777 = 1/10 + 0.0777..
(0.777 needs to be shown to be 7/90 to gain first M1)
Total 2 marks
16/90 oe
3.
Working
)
Total 2 marks
x = 0.1777.... and 10x = 1.777..
9x = 1.6
Question
or equivalent fraction (but not
Answer
Mark
4.2
1.12
2
3.75
Notes
1
for 4.2 or 1.12 or 0.6 or
15
4
A1
Total 2 marks
4.
(x =) 0.01515.. and (100x =) 1.515...
99x = 1.5
15/990 oe
2
1/ 66 *
M1
or 10x = 0.1515..and 1000x = 15.1515.. selected
A1 but not 1/66 Numerator and denominator have to be integers.
* nswer given
Total 2 marks
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Question
5.
Working
x = 0.3888888...
10x = 3.88888...
9x = 3.5
3.5
x=
9
Answer
Mark
M1
x=
3.5
9
2
A1
for method as far
as attempting to
subtract
eg 1000x = 388.8888...
10x = 3.88888...
990x = 385
385
x=
990
3.5
7
or equivalent fraction or 18x = 7 before reaching
must reach
9
18
Total 2 marks
x = 0.417417 ….
1000x = 417.417 …
999x = 417
6.
Notes
eg 100x = 38.88888...
10x = 3.88888...
90x = 35
35
x=
90
M1 for 1000x = 417.417… and x = 0.417417…


accept x = 0.417 selected for use oe
2
show
A1for
417
cso
999
Total 2 marks
7.
eg.
x= 0.2666… and 10x = 2.666… or
10x = 2.666… and 100x = 26.66…
M1
show
w
A1
Two correct decimals that, when subtracted, will
leave a non-recurring value with intention to
subtract.
Must see a recurring symbol or 3+ sixes.
Must see a fraction prior to seeing
4
15
Alternative method
eg. x = 0.0666… and 100x = 6.666
with subtraction
2
M1
for conversion of 0.0666… to a fraction
A1
for conclusion with all steps seen
Total 2 marks