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Number Detective

Follow the clues to find the mystery number.

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?

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?

More Carroll Diagrams

Age 7 to 11 Challenge Level:

Can you put the numbers in the correct place in this Carroll diagram?

You could print off this sheet.pdf.

Can you explain how you know where to place the numbers?


Now have a look at this Carroll diagram. This time, the idea is to fill in the labels for the rows and columns.

You could print off sheet.pdf to complete.