# Diagram

In the given diagram, what is the value of x ?

A. 20^{o}

B. 60^{o}

C. 80^{o}

D. 100^{o}

E. 120^{o}

**Answer ?**

# Canadian Open Mathematics Challenge 2007

**Problem:**

1. If a = 15 and b = -9, what is the value of a^{2} + 2ab + b^{2} ?

2. A circular wind power generator turns at a rate of 30 complete revolutions per

minute. Through how many degrees does it turn in one second ?

Solution ?

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# Mathematics Challenge

**Problem:**

1. If 2x + y = 13 and x + 2y = 11, what is the value of x + y?

2. Determine the units digit of the integer equal to 9 + 9^{2} + 9^{3} + 9^{4}.

(The units digit of an integer is its rightmost digit. For example, the units digit of

the integer 1234 is 4.)

Answer ?

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# Arithmetic Series

Determine the value of

-1 + 2 – 3 + 4 – 5 + 6 – 7 + 8 – 9 + 10 – 11 + 12 – 13 + 14 – 15 + 16 – 17 + 18

Answer ?

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# Canadian Mathematics Competition

1. Pat planned to place patio stone in a rectangular garden that has dimensions 15 m by by 2m. If each patio stones measure 0.5 m by 0.5 m, how many stones are needed to cover the garden ?

A. 240

B. 180

C. 120

D. 60

2. The prime numbers between 10 and 20 are needed together to form the number Q. What was the larges prime number divisor of Q ?

A. 2

B. 3

C. 5

D. 7

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