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Number Detective

Follow the clues to find the mystery number.

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Red Even

You have 4 red and 5 blue counters. How many ways can they be placed on a 3 by 3 grid so that all the rows columns and diagonals have an even number of red counters?

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Diagonal Trace

You can trace over all of the diagonals of a pentagon without lifting your pencil and without going over any more than once. Can the same thing be done with a hexagon or with a heptagon?

Light the Lights

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2
How will you keep track of what happens with each number you try?
You might find a hundred square useful.