SEA Maths 2023
SEA Maths 2023
SEA Maths 2023
Section 1
Since all digits in the thousands column have the same value, we start by observing
the next column which is the hundreds column.
The digit with the largest value is 6. So, 3 612 is the largest of the four numbers.
The next largest digit is 2, so 3 261 is the second largest number.
We now move to the tens column and examine the tens digit in the two remaining
numbers which are 3 162 and 3 126. Their tens digits are 6 and 2.
Since 6 is larger than 2, then 3162 is larger than 3126.
So, 3 162 is the third largest number and 3 126 is the smallest of the given four
numbers.
8 Alternatively:
1=
8 3 ( 2 ´ 8) + 3
2 =
8 16 8 8
2 = 2´ =
8 8 16 + 3
=
3 16 3 8
2 = +
8 8 8 19
=
19 8
=
8
19
Answer:
8
052
12 6 2 8
-6 0 ¯
28
-2 4
4 (Remainder)
4 1
Answer: 52 with remainder 4 or 52 or 52 in its lowest form
12 3
5. 82 + 62 =
82 + 6 2 = ( 8 ´ 8 ) + ( 6 ´ 6 )
= 64 + 36
= 100
Answer: 100
In rounding to the nearest thousand, we need to express this number in thousands or larger.
The digits to the right of the thousands digit will be replaced by zero.
The value of the digit to the immediate right of the thousands digit is critical in deciding if
the number of thousands must be increased or not. We refer to the hundreds digit, in this
case, as the deciding digit. If this digit is less than 5, we round down and if it is 5 or more,
we round up by adding one thousand to the thousands digit.
Answer: 15 000
1
7. Max ate 5 cherries which were of the total number of cherries he picked. How many
9
cherries did Max pick?
1
If 5 cherries were of the number picked, then, the number of cherries picked is
9
5 × 9 = 45
Alternatively:
1
of the number of cherries picked is 5.
9
The whole has 9 equal parts, and one part is 5.
Answer: $46.05
15
15% =
100
15
15% of 120 = ´ 12 0
10 0
3
15
= ´12
2 10
6
3 ´ 12
=
21
= 3´ 6
= 18
Answer: 18
The two largest digits are 3 and 4. These two digits are placed in the tens column. It
doesn’t matter where the last two digits, 1 and 2 are placed. Either with the 3 or the 4
will make no difference in the final sum.
Answer:
Tens Units Tens Units
(10) (1) OR. (10) (1)
4 1 4 2
+ 3 2 + 3 1
7 3 7 3
11. A part of the calendar for the month of April is shown below.
April
Sun Mon Tue Wed Thu Fri Sat
10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25
April
Sun Mon Tue Wed Thu Fri Sat
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
Answer: Sunday
Alternatively:
Mass of the pawpaw is
1 kg = 1000 g
3 . 5 0 kg \ 0.75 kg = 1000 ´ 0.75
- 2 . 7 5 kg = 750 g
0 . 7 5 kg
Answer: 40 cubes
14. Calculate the difference in length between the eraser and the pen.
1 cm 4 cm 6 cm 17 cm
\Length of eraser = (4 – 1) cm
= 3cm
The difference in length between the pen and the eraser = (11 – 3) cm = 8 cm
Answer: 8 cm
The four slant edges of the pyramid are therefore each of length 6 cm.
Answer: 4 edges
Answer: C
In the above triangle all three sides are unequal in length. The triangle is called scalene.
Answer: Scalene
18. The table below shows the show sizes of some students.
Shoe Size 9 8 7 6 5
Number of Students 11 3 12 9 3
The shoe size with the highest frequency represents the mode.
The shoe size 7 occurs 12 times.
Since 12 is highest frequency, the modal shoe size is 7.
Answer: 7
32 14 24 0 5 32
14
Total of all numbers: 32 + 14 + 24 + 0 + 5 = 75 24
0
There are 5 numbers. + 5
75
Total of the numbers !"
Mean = = " = 15
Number of numbers
Answer: 15
Complete the tally chart to show the number of students who own dogs.
9 2 1
- 2 6 3 7
6 5 8
Consider the ones column, we cannot subtract 7 ones from 1 one, so we re-group:
2 tens and 1 ten and 11 ones as shown below:
Th H T O
1 11
9 2 1
–2 6 3 7
6 5 8 4
– 2 637 = 6 584
= 6 584 + 2 637
= 9 221
9
Answer: 3
14
How many metres of cloth would she need to make 12 similar skirts?
65× 12
=(60 × 12) + (5 × 12)
= 720 + 60 = 780
60 ´18
Explain who had the better estimate and how it was calculated.
10 18 20
Since 18 is closer to 20 than 10, rounding 18 to 20 will give a better estimate than
rounding 18 to 10.
• The difference between Kim’s estimate and the exact value is 1080 – 600 = 480
• The difference between Ben’s estimate and the exact value is 1200-1080 =120
Ben’s estimate is closer to the exact value than Kim’s estimate since 120 is less than
480.
Ben, therefore, has the better estimate.
What is the difference in the price of a packet of milk at Shop A and Shop B?
The difference in cost of a packet of milk at Shop B and Shop A = $7.60 - $6.50
= $1.10
We know that the whole is $85. So, we can combine all the shares to make $85.
This $40 is part of the $85, so we subtract it from $85 to get: $85 – $40 = $45
What remains is 3 equal units where each unit represents Tom’s share.
1 cap
1 bag
= $20
Answer: $20
Hence, following the pattern, the number of squares in the 11th element = 11 + 12 + 13
= 36
Answer: 36 squares
The rule for the number of squares is always the sum of three numbers.
The first number is the number of the pattern. The second number is the number of
pattern + 1. The third number of the pattern is the number of pattern + 2.
So, if the number of the pattern is n, then the 1st number is n, the 2nd number will be
n + 1 and the third number will be n + 2 .
Calculate the difference between the perimeter of one square and the perimeter of the
rectangle ABCD.
Difference between the perimeter of the rectangle and the perimeter of the square
= (120–48) cm
= 72 cm
Answer: 72 cm
Since the luggage was above by 5 kg when both items were present and it was below
by 500 g after removing both items, then the hairdryer and the shampoo together weigh
5 kg + 500g = 5.5 kg.
Alternatively
Since the luggage was below the limit by 500g without the hairdryer and shampoo, and
2 kg over the limit after putting in the hairdryer, the hairdryer must weigh:
2 kg + 0.5 kg = 2.5 kg = 2 500g
0.5 kg 2 kg 5 kg
No items HD only HD + S
Write the name of the quadrilateral that matches the properties given.
Properties Name
No lines of symmetry, one pair of parallel
sides, one angle greater than a right angle
The figure with no lines of The figure with two lines of symmetry, two pairs of
symmetry, one pair of parallel parallel sides, not right angles is the given rhombus.
sides, one angle greater than a right
angle is the given trapezium.
Properties Name
No lines of symmetry, one pair of parallel sides,
one angle greater than a right angle Trapezium
Two lines of symmetry, two pairs of parallel
sides, not right angles Rhombus
We reflect each vertex of the given figure in the line AB. Each reflected vertex would
lie on the opposite side of AB and the same distance from AB. This can be located by
counting the blocks. The new vertices are now connected by straight lines to complete
the symmetrical figure.
The completed shape looks like:
Hence, in Match 3 the number of runs scored is four blocks high and will represent
20 ´ 4 = 80 runs
Answer: 80 runs
English
Subject Science Mathematics Art Music Language
Arts
Mark 80 55 47 73
Answer: 85 marks
37. Tara bought an equal number of pies and doughnuts. She spent a total of $70.
Pies Doughnuts
Tara can buy pies in sets of two and she can buy doughnuts in sets of three.
For equal numbers of pies and doughnuts, the options are 6, 12, … or multiples of 6.
If Tara spent $70 then she must have bought twice as many as 6 of each of the items
since $70 = $35 × 2.
Answer: 12 pies
Dave stuck 13 strips of Bristol board, each of length 15 cm to make the decoration.
Assuming Dave overlaps the strips by placing 4 cm of the second strip over the first
strip and then continues in this manner. Starting from the first strip, each strip will have
a 4 cm overlap at its right end, so that only 15 – 4 = 11 cm will be exposed. Assuming
he had only 5 strips, then the 5th strip will have no overlap on its right end and so15 cm
will be exposed.
11 cm 11 cm 11 cm 11 cm 15 cm
1 2 3 4 5
4 cm 4 cm 4 cm 4 cm
Right angle at C.
Reflex angle at B.
Alternatively:
F G
This shape has
Right angle at G.
K H
a) What is the lowest score that Brandy should obtain in Round 3 to qualify for a
silver medal?
Hence, the lowest score that Brandy needs in Round 3 is 273 - 172 = 101
b) Clara’s total score was 140. Her score in Round 2 was three times her score in
Round 3.
What was Clara’s score in Round 3?
Answer: 23 points