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## 'Domino Join Up' printed from http://nrich.maths.org/

You will need a double-six set of dominoes for this
problem (a standard set of dominoes) but without the
seven doubles (double one, double two etc). That is twenty-one
domino pieces in all.

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.