SEAMO X 2019 — Paper B — Grade 3–4

Find the missing number: $1,1,4,10,28,(\quad),\ldots$.

Cabinets $A,B$ contain $840$ books altogether. After $40$ books are moved from $A$ to $B$, $A$ has one third as many as $B$. How many books were originally in $A$?

Given $3\triangle4=3+4+5+6+7=25$ and $6\triangle3=6+7+8+9=30$, find $5\triangle5$.

Place the numbers $1,2,\ldots,8$ once each in the small circles so that the five numbers on each large circle sum to $21$.

Evaluate $1-3+5-7+9-11+13-\cdots-39+41$.

The picture shows two squares $A,B$. The area of $A$ is $40\text{ cm}^2$ greater than the area of $B$. Find the side length of $A$.

Find $x$ in $(4x+112-20)\div4=100$.

A competition has $15$ questions. A correct answer earns $10$ marks; a wrong or unattempted answer loses $4$ marks. John scores $108$. How many answers are correct?

Which figure has a different shaded area from the others?

Mao Mao is $8$ and her mum is $40$. How many years later will Mum be three times as old as Mao Mao?

How many triangles are in the figure?

A teacher gives sweets to a class. Giving $8$ per student requires $7$ more sweets. Giving $7$ per student leaves $8$. Find (a) the number of students and (b) the number of sweets.

The figures follow the staircase pattern of unit squares of side $1\text{ cm}$. Find the perimeter of a figure formed by $78$ squares.

The source says $a,b$ are whole numbers and prints $1155\times\boxed{\phantom{a}}=210\times b$. Find $a+b$.

Grass grows at a constant rate. $27$ cows finish the grass in $6$ days; $23$ cows finish it in $9$ days. How many days will it sustain $21$ cows?