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Number Detective

Follow the clues to find the mystery number.

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Red Even

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Prime Magic

Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?

Number Differences

Stage: 2 Challenge Level: Challenge Level:1

Try putting any number in one square to start with.
What numbers could go in the squares which join this first square? What do all these options have in common? Can this help you find other arrangements of the numbers?
You might like to print out this sheet of blank grids if you are not using the interactivity.