hougang primary school mathematics department · 2016. 9. 18. · final note regular revision by...

Hougang Primary School

Mathematics Department

Parent Workshop 2016

Types of PSLE Questions

Computation

cccc

Example 1

1 + 2 + 3 + 4 + …….. + 94 + 95 + 96 + 97

When the first 97 whole numbers are

added up, what is the digit in the ones

place of this total?

(1) 1

(2) 2

(3) 3

(4) 8

1 + 2 + 3 + 4 + …….. + 94 + 95 + 96 + 97

1 + 2 + 3 + 4 + …….. + 94 + 95 + 96 + 97

1 + 2 + 3 + 4 + …….. + 94 + 95 + 96 + 97

1 + 2 + 3 + 4 +5 …+ 50+….. + 94 + 95 + 96 + 97

100

100

100

= 100 x 47 + 1 + 2 +50

= 4700 + 53

=4753

Example 1

1 + 2 + 3 + 4 + …….. + 94 + 95 + 96 + 97

When the first 97 whole numbers are

added up, what is the digit in the ones

place of this total?

(1) 1

(2) 2

(3) 3

(4) 8

Ans : (3)

Example 2

A repeated pattern is formed using the numbers

1 and 0. The first 18 numbers are shown below.

1 0 1 0 1 1 1 0 1 0 1 1 1 0 1 0 1 1

1st 19th

What is the sum of the first 100 numbers?

(1) 60

(2) 64

(3) 66

(4) 68 2013 PSLE

There are 6 numbers in 1 group.

There are altogether 100 numbers.

How many groups are there? What is the

remainder?

100 ÷ 6 = 16 R 4

.

R1 R2 R3 R4

1 0 1 0

1 0 1 0 1 1 1 0 1 0 1 1 1 0 1 0 1 1

1st 18th

Sum of each group ------------1 + 0 + 1 + 0 + 1+ 1 = 4

Sum of 100 numbers ---------- 4 x 16 + 1 + 1 =66

Example 3

Other computation questions Round off 70.171 to the nearest tenth.

Find the value of 4.8 + 0.29.

Express 1090 cm in m

A solid cuboid of height 10 cm has a square base of

side 3 cm. What is its volume?

Zaleha bought 1.2kg of grapes. 100 g of grapes cost

70 cent. How much did she pay?

Tips to nail the computation

questions

Firm foundation in number bonds.

Must know the multiplication tables very well.

Encourage children to use mental sum tricks

Example:

0.46 x 70 = 0.46 x 7 x 10

= 3.22 x 10

= 32.2

Types of PSLE Questions

Scale reading

Three containers with some water are shown below.

Which container has the most water?

160 ml 150 ml 200 ml

Container C contains the most water

50 20

=500ml

0.1

or

100

ml

Concepts tested along with

Procedures

A number when divided by 30 gives a remainder of 8.

Which of the following can be added to the number to

change it to a multiple of 6?

Spatial Visualisation

Question 1

In the figure below, ABDF and BCEF are rectangles and

CDE is a straight line. AB = 6 cm, AF = 8 cm and

BF = 10 cm. Find the length of BC

10cm

B

A

C

D

E

F

6 cm

8 cm

Question 2

MQN is an equilateral triangle

QPM is an isosceles triangle

MPQ = ( 180 – 30 ) ÷2 = 75

MPN = 75 x 2 = 150

60o

60o

60o

30o

Question 4

In the figure below, a rectangular piece of paper is folded

at 2 of its corners A and C as shown. Find ABC

Practical Questions

In the square grid below, PQ and QR are straight lines.

(a) Measure and write down the size of PQR

(b) PQ and QR form 2 sides of a trapezium PQRS. PS is

parallel to QR. PS is twice the length of QR. Complete

the drawing of the trapezium PQRS.

Word Problems

Understand

Plan/Devise

Do/Carry Out

Check

Understand • What am I given? (information , data)

• What am I asked to find?

• How can I make sense of the information

given to me? (Keywords, models, tables )

Plan/Devise • What strategy should I use?

• Have I solved similar problems before?

Strategies / Heuristics

Working backwards

Make a table

Systematic listing

Pattern Recognition

Assumption

Guess and Check

Model Drawing

Before and After concept

Do/Carry Out

• Are my steps accurate?

• Are there traps that I need to be alert of?

• Have I used all the information?

• Do my steps make sense?

Check • Does my answer make sense?

• Did I answer the question?

• Could this problem be solved in a simpler

way?

Question 1

Meng sold a total of 368 large and small durians at

the prices shown below and collected $2760. How

many large durians did Meng sell?

Durian for Sale

Large $9 Small $5

2 totals given

Plan :

Assumption

Guess & Check

Assumption

Assume all are small durians.

Cost of durians ----- 368 x $5 = $1840

Difference between actual cost and assumed cost

----- $2760 - $1840 = $920

$5 $5 $5

………

No of large durians ------- $920 ÷ $ 4 = 230

Question 2

Robin bought some pens for $42. He bought the same

number of rulers for $22. Each pen cost $2 more than

each ruler.

How many rulers did Robin buy?

Same number

of rulers

1 Pen is more

expensive than

1 ruler

Plan :

Differences

Since the number of rulers and pens are the

same

No of

pens:

No of

rulers :

$42

$22

$42 - $22 = $20

$20 ÷ $2 = 10

Robin bought 10 rulers.

Question 2

160 more

chickens than

duck

Plan : model

drawing

ducks

chickens

S

S

S

L

S S L L

160

80

S

80

L

3 units + 80 ------- 230

3 units -------- 230 – 80 = 150

1 units -------- 150 ÷ 3 = 50

There are 50 ducks left.

Question 3

The ratio of the number of books to the number of files

was 7 : 2.

When 20 books and 25 files were added, the ratio

became 2 : 1.

How many files were there at first?

2 different

types of units

Plan :

units and parts

Before and after

Units and Parts

Books Files

Before

After

7 units + 20 ----------- 2 parts

2 units + 25 ----------- 1 part

7 units 2 units

+20 books +25 files

2 parts 1 part

(

)

4 units + 50 ----------- 2 parts

7 units +20 ---------- 4 units + 50

X2

7 units +20 ---------- 4 units + 50

3 units ---------- 50 – 20 = 30

1 unit --------- 30 ÷ 3 = 10

2 units -------- 10 x 2 = 20

There were 20 files at first.

Question 5

Ishak uses rods to form figures that follow a pattern. The

first four figures are shown below.

How many rods would he use for Figure 30?

Figure Number Number of rods used

1 10

2 15

3 18

4 23

Numbers

increase at

regular

intervals

Figure Number Number of rods used

1 10

2 15

3 18

4 23

5 23 + 3 = 26

6 26 + 5 = 31

7 31 + 3 = 34

…… …….

30 127

+ 5

+ 3

Systematic Listing

Grouping

Figure Number Number of rods used

1 10

2 15

3 18

4 23

+2 +8

Number of figure from Figure 4 to Figure 30

= 30 – 4 = 26

Number of increases of 8 rods from Fig 4 to 30

= 26 ÷ 2 = 13

Number of rods in Figure 30

= 23 + 13 x 8 = 127

Final Note

Regular revision by re-doing questions that your child has

done wrongly.

Encourage your child to simplify the problem by drawing

models (pictures) or presenting the information in a

table.

Ensure adequate and productive practice.

Provide opportunities for time-based practices.

Ground the basics first before moving on to challenging

problems.

Remind your child to start with the simpler questions and

move on if he is stuck.