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Can you arrange fifteen of the pieces round a track like this so that all the touching domino pieces add to $6$ and the ends join up?
You will have six pieces left over.
Using the same twenty-one pieces, can you now make all the joins add to $7$? Which six pieces will you have to leave out?
Can you now make all the joins add to $5$ using the twenty-one pieces? Which six pieces will you have to leave out now?
Now can you make all the joins add to make an even number? What about all the joins adding to make an odd number?
You may find our Dominoes Environment useful for working on this problem.
Printable NRICH Roadshow resources: Instructions and Domino Track.Six new homes are being built! They can be detached, semi-detached or terraced houses. How many different combinations of these can you find?
Start with four numbers at the corners of a square and put the total of two corners in the middle of that side. Keep going... Can you estimate what the size of the last four numbers will be?