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Age 7 to 11

Challenge Level

- Problem
- Student Solutions
- Teachers' Resources

Thank you to everybody who sent in their ideas about this task.

Rhys and Jack from Castle Cove Public School in Australia sent us this solution to Challenge 3:

They said:

We chose to use the strategy 'guess and check' because we could experiment with different combinations of Lego blocks. We thought we had the answer but then we checked and found that it was wrong. We kept on trying adding and taking away blocks from the rows and columns and finally got the answer. What we got was 13 long 4 wide and 3 up = 112 blocks.

Good ideas, Rhys and Jack, and your solution is correct! There are two other possible solutions for Challenge 3. If anybody thinks they have found them, please do email us. (Thank you to Deborah, a teacher in London, who kindly got in touch with us to point out there are two others, when we had thought there was only one more solution!)

Jonny from Dame Bradbury's in the UK worked on this problem with his Maths teacher and they sent in their solution. You can click on the picture below to make it bigger:

Great ideas, Jonny - you have correct solutions for Challenge 1 and Challenge 2, but your solution for Challenge 3 isn't quite right.

Jonny said:

We still could only find two of the solutions for Challenge 4.

I think you've actually found three solutions for Challenge 4, Jonny, as there is one possibility that you haven't highlighted that totals 146 in your solutions. There is one more possibility for Challenge 4 - if anybody thinks they've found it, please email us.