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April's Problem
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The coordinates of the vertices of quadrilateral ABCD are:

A(-4,-3), B(4,2), C(2,-2), and D(6,-5).

What is the area of quadrilateral ABCD?

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A solution to this problem will appear along with next month’s problem.
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March's Problem
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The average (mean) of three numbers is 5/6. Two of the three numbers are 1/2 and 2/3. What is the third number in lowest terms?

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METHOD 1: Find the sum of the three.
Since the average of the three numbers is their sum divided by 3, their sum is 3 times their average. Thus, the sum of the three numbers is 5/6 x 3 = 15/6. Then 1/2 + 2/3 + the third number is equal to 15/6. The third number is 15/6 - 1/2 - 2/3 = 4/3 or 1 1/3.

METHOD 2: Find Use Algebra.
5/6 = 1/3( 1/2 + 2/3 + x) [Distribute 1/3 to each term in the parentheses.]
5/6 = 1/6 + 2/9 + x/3 [Combine number terms.]
15/18 = 7/18 + x/3 [Combine.]
8/18 = x/3 [Multiply both sides by 3.]
24/18 = x So x = 4/3.

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February's Problem
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A large cube 2 meters along each edge is cut into small cubes that are 2 centimeters along each edge. How many small cubes are there?

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METHOD: Determine the number of cubes on an edge
2 m = 100 × 2 cm. So there are 100 small cubes along each edge. Since a cube is three dimensional, the large cube is cut into 100 × 100 × 100 = 1,000,000 small cubes.
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For many additional problems we highly recommend the following books:

Math Olympiad Contest Problems for Elementary and Middle Schools by Dr. G. Lenchner
and
Math Olympiad Contest Problems Volume 2 edited by Richard Kalman
and
MOEMS® Contest Problems Volume 3
edited by Richard Kalman & Nicholas J. Restivo.
are sources of many such problems.

Creative Problem Solving in School Mathematics 2nd Edition by Dr. George Lenchner
can help you to teach solving these types of problems