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SEAMO 2026 Paper B — Organizer self-practice SET 4

Question 1

Find the value of $1\div(2\div3)\div(3\div4)\div(4\div5)\div(5\div6)$.
  1. 2
  2. 3
  3. 4
  4. 5
  5. 6

Question 2

Find the number represented by the last figure.

Question illustration
  1. 13
  2. 23
  3. 31
  4. 32
  5. 33

Question 3

How many dots will there be in the 8th figure?

Question illustration
  1. 42
  2. 44
  3. 46
  4. 48
  5. None of the above

Question 4

A new operation is defined by $M\mathbin{\forall}N=4M-3N$. Find $x$ if $x\mathbin{\forall}1=17$.
  1. 3
  2. 4
  3. 5
  4. 6
  5. 7

Question 5

In the figure, $ABCD$ is a square of side 5 cm; $B,C,E$ lie on a straight line and $CE=a$. The shaded region $y$ is 5 cm² larger than the shaded region $x$. Find $a$.

Question illustration
  1. 7 cm
  2. 8 cm
  3. 9 cm
  4. 10 cm
  5. None of the above

Question 6

The diagonal of a square is 12 cm, as shown. What is its area in cm²?

Question illustration
  1. 68
  2. 72
  3. 74
  4. 76
  5. 80

Question 7

A prime number is a whole number with exactly two positive factors, 1 and itself. Examples are 2, 3, 5, 7, 11, 13, … . Two prime numbers have sum 34. Find their smallest possible product.
  1. 48
  2. 54
  3. 72
  4. 88
  5. 93

Question 9

How many numbers are in the sequence $4,10,16,22,28,\ldots,64$?
  1. 8
  2. 10
  3. 12
  4. 14
  5. None of the above

Question 10

Marvin wrote the sequence $1,2,3,4,5,6,7,\ldots$ on the whiteboard. What is the 177th digit he wrote?
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

Question 11

How many digits are in $1111111\times1111111$?
  1. 13
  2. 14
  3. 15
  4. 16
  5. None of the above

Question 12

Find $1-2+3-4+5-6+7-\cdots-2018+2019$.
  1. 840
  2. 1010
  3. 1060
  4. 2000
  5. 2018

Question 13

Nutcharat drove from Chiang Mai to Bangkok at 120 km/h, then returned along the same route at 80 km/h. What was her average speed for the entire trip?
  1. 93 km/h
  2. 94 km/h
  3. 95 km/h
  4. 96 km/h
  5. 100 km/h

Question 14

Emma’s wallet was stolen. Adam, Ben and Charles were the suspects.

Adam: “Ben stole the wallet!”

Ben: “Not me!”

Charles: “It wasn’t me.”

Only one person told the truth. Who stole the wallet?
  1. Adam
  2. Ben
  3. Charles
  4. Adam and Ben
  5. Impossible to determine

Question 15

What is the largest four-digit common multiple of 5 and 8?
  1. 9900
  2. 9920
  3. 9940
  4. 9960
  5. None of the above

Question 16

What is the first number in the 10th row of the array?

Question illustration
  1. 163
  2. 165
  3. 167
  4. 169
  5. None of the above

Question 17

In mathematics, $A>B$ means A is larger than B, and $A<B$ means A is smaller than B. Given $A=98765\times87654$ and $B=98756\times87663$, which statement is true?
  1. $A>B$
  2. $A<B$
  3. $A=B$
  4. Impossible to determine
  5. None of the above

Question 18

The school rented boats for 48 students. A small boat holds 3 students and costs 4 dollars to rent. A big boat holds 5 students and costs 6 dollars. What is the minimum total rental cost?
  1. 54 dollars
  2. 55 dollars
  3. 56 dollars
  4. 57 dollars
  5. 58 dollars

Question 19

A basket contains apples. First, 2 more than half the apples are removed. Then, 2 less than half the remaining apples are removed. Finally, 20 apples remain. How many apples were there at first?
  1. 76
  2. 72
  3. 64
  4. 58
  5. 48

Question 20

How many squares are there in the $4\times4$ grid?

Question illustration
  1. 28
  2. 30
  3. 32
  4. 34
  5. 36