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Number Detective

Follow the clues to find the mystery number.

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Make 37

Four bags contain a large number of 1s, 3s, 5s and 7s. Pick any ten numbers from the bags above so that their total is 37.

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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?

Red Even

Age 7 to 11 Challenge Level:

You have 4 even numbers and 5 odd numbers and all the totals are odd. Think of the red counters as even numbers and the blues as odds. If diagonals can have any total then all three configurations give equivalent solutions because one can be transformed into another by interchanging rows or interchanging columns. If diagonals also have prime totals then only configuration (a) is possible