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Age 11 to 14 Short
Challenge Level
In how many different ways can seven different numbers be chosen from the numbers $1$ to $9$ so that the seven numbers have a total which is a multiple of $3$?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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NRICH is part of the family of activities in the Millennium Mathematics Project.
NRICH is part of the family of activities in the Millennium Mathematics Project.