We investigated some questions from the past years’ Kangaroo contest (2012 – 2013). Three questions were left for a further discussion.

**Kangaroo Canada 2012 G6 Question 15:**

**Answer**:

We make the every 4 respective cells repeated since the sum of any four consecutive numbers is 12. In each 4 cells unit [1,2,3,4], we know

unit[1] = 1 –> unit[2] = ? –> unit[3] = 2 –> unit[4] = 4

unit[*smilingFace*] is in unit[2] = 12 – unit[1] – unit[3] – unit[4] = 12 -1-2-4 = 5

The answer is D.

**Kangaroo Canada 2012 G6 Question 28:**

**Answer**:

Ann to Bill >> I do not know your number. It does mean Ann does not hold 1;

Bill to Ann >> I do not know your number. It does mean Bill does not hold 1;

The next option will be started from 2. Ann knows her own number **a***, *Bill’s number is either * b=a-1 *or

*Ann to Bill>>I know your number is a factor of 20, number will be one of 2,4,5,10,20. We know both*

**b=a+1**.**a**

**-1**and**are factors of 20 must be 2 and 4, therefore,**

*a+1**=3. The answer is C.*

**a****Kangaroo Canada 2012 G6 Question 29:**

**Answer**:

The hint is that the folding process is actually dividing the square to 8 parts side by the diagonal, the each side will be divided to 4 units. Based on “The area of the original square is 64 “, we know the side = 8 cm, each unit is 2 cm. Then we can find that the shadow is 2×4 rectangle. The answer is C.