### 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?

# Various Venns

##### Age 7 to 11 Challenge Level:

Can you place the numbers from $0$ to $51$ into this Venn diagram?
How do you know where to put each number?
You might like to print off this sheet if you do not want to use the interactivity.

Full Screen Version

Here is another one for you to try. If you'd prefer to work on paper, print off this sheet.
Full Screen Version

The third Venn diagram below is a little different. This time you need to decide what sets the two groups represent. Choose the labels from the list on the right.

Here is a sheet you can print.
Full Screen Version

Can you explain how you worked it out?