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SASMO 2022 Grade 8

Question 1

Scoring for this entire paper: on this platform, start at 0; Q1–15 earn 2 points each and Q16–25 earn 4 points each. Incorrect or blank answers earn 0; maximum 70. Official SASMO rules: start with 15 points; Section A (Q1–15) awards +2/−1/0 for correct/incorrect/blank, and Section B (Q16–25) awards +4/0/0; maximum 85.

Find the value of $56\times7\times125$.
  1. 40900
  2. 49000
  3. 50000
  4. 4900
  5. None of the above

Question 2

How many consecutive zeros are there at the end of $6^8\times10^3\times8^2\times25^5$?
  1. 14
  2. 13
  3. 10
  4. 8
  5. None of the above

Question 3

A rectangle was made of 100 identical squares. If we remove 1 square from each row and add 5 squares to each column, there will still be 100 squares in the new rectangle. How many columns are there in the original rectangle?
  1. 4
  2. 5
  3. 20
  4. 25
  5. None of the above

Question 4

The figure below is made of a circle, a square and a regular hexagon. The circle is centred at $O$ and has an area of $36\text{ cm}^2$. The total area of the unshaded regions in the square and hexagon is 3 times the area of the shaded region. What is the combined area (in $\text{cm}^2$) of the square and hexagon? Use the arrangement shown: $O$ is their common vertex, and the shaded parts are the circle sectors inside the two polygons.

Question illustration
  1. 21 cm²
  2. 63 cm²
  3. 72 cm²
  4. 84 cm²
  5. None of the above

Question 5

If $a>5$, simplify $\left|2-\sqrt{(3-a)^2}\right|$.
  1. $5-a$
  2. $a-5$
  3. $-1-a$
  4. $a+1$
  5. None of the above

Question 6

Which cube will be formed when the net below is folded? The letters A–E label the five original choices in the picture. Fold so that the printed faces are on the outside.

Question illustration
  1. Cube A
  2. Cube B
  3. Cube C
  4. Cube D
  5. Cube E

Question 7

What is the next number in the sequence $2,9,28,65,126,\ldots$? Use the intended simple pattern; a finite list alone does not determine a unique continuation.
  1. 216
  2. 217
  3. 343
  4. 344
  5. None of the above

Question 8

The integer $a$ is a multiple of 3 but not a multiple of 6. Which of the following is NOT an odd number?
  1. $a+6$
  2. $a-10$
  3. $3a+4$
  4. $7a+1$
  5. None of the above

Question 9

A certain month has 3 Tuesdays falling on even-numbered dates. Which day is the 26th of this month?
  1. Friday
  2. Monday
  3. Wednesday
  4. Thursday
  5. None of the above

Question 10

The five-digit number $\overline{A85A2}$ is a multiple of 12. If $A$ is not a prime number, find its value.
  1. 1
  2. 3
  3. 6
  4. 9
  5. None of the above

Question 11

The operator $\otimes$ acts on two integers to give the following outcomes: $$4\otimes8=818,\quad3\otimes6=616,$$ $$6\otimes12=1222,\quad10\otimes12=2022.$$ What is $20\otimes22$? Use the intended pattern: apply a fixed simple operation separately to each input, then concatenate the two decimal results. These examples are a pattern puzzle, not a unique definition on all integers.
  1. 2022
  2. 4032
  3. 2232
  4. 4022
  5. None of the above

Question 12

An integer is called beprisque if its two neighbouring integers are a perfect square and a prime number, in either order. For example, 8 is a beprisque number. How many 2-digit beprisque numbers are there?
  1. 4
  2. 5
  3. 6
  4. 9
  5. None of the above

Question 13

How many 4-digit numbers are there whose sum of the digits is 33?
  1. 8
  2. 14
  3. 20
  4. 24
  5. None of the above

Question 14

In how many ways can 63 be expressed as the sum of two or more consecutive positive integers?
  1. 2
  2. 3
  3. 4
  4. 5
  5. None of the above

Question 15

In square $ABCD$, points $E$ and $F$ lie on sides $AD$ and $CD$, respectively, with $3DE=3FC=AB$. Segments $BF$ and $CE$ intersect at $G$. If the square has area $180\text{ cm}^2$, what is the area (in $\text{cm}^2$) of quadrilateral $EDFG$?

Question illustration
  1. 9 cm²
  2. 18 cm²
  3. 27 cm²
  4. 36 cm²
  5. None of the above

Question 16

What is the sum of the digits of $3006\times\underbrace{111\ldots111}_{100\text{ ones}}$?

Answer format: enter one whole number without units; leading zeros are optional. The source answer sheet uses four digits (for example, 7 is shaded as 0007).

Question 17

A train travelling at 108 km/h crosses a bridge in 40 seconds and a man standing on the bridge in 24 seconds. What is the length (in metres) of the bridge? Assume constant speed, and measure each crossing from the front entering until the rear has passed.

Answer format: enter one whole number without units; leading zeros are optional. The source answer sheet uses four digits (for example, 7 is shaded as 0007).

Question 18

What is the sum of the digits of $A=5555555^2-4444444^2$?

Answer format: enter one whole number without units; leading zeros are optional. The source answer sheet uses four digits (for example, 7 is shaded as 0007).

Question 19

Let the operation $\triangle$ be given by these examples: $$3\triangle3=2+3+4,\qquad5\triangle2=4+5,$$ $$9\triangle6=8+9+10+11+12+13.$$ If $164\triangle x=2022$, find $x$. Interpret $a\triangle b$ as the sum of $b$ consecutive integers starting at $a-1$, with $b$ a positive integer, as intended by the source.

Answer format: enter one whole number without units; leading zeros are optional. The source answer sheet uses four digits (for example, 7 is shaded as 0007).

Question 20

A machine converts any positive integer into a two-digit code as follows:
1. The first digit is the remainder when the integer is divided by 8.
2. The second digit is the remainder when it is divided by 13.
3. If the remainder on division by 13 is greater than 9, the second digit is just 9.
For example, 17 becomes 14. What is the smallest positive integer that becomes 12?

Answer format: enter one whole number without units; leading zeros are optional. The source answer sheet uses four digits (for example, 7 is shaded as 0007).