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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:

(a) 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?

(b) It is now only required that all the rows and columns have an even number of red counters. Are there any additional solutions? Two solutions are considered the same if one can be transformed to the other by rotating the square.