Stage: 2 Challenge Level: 
Why do this problem?
This problem requires only simple adding, but also persistence and logical thinking.Key questions
What do one, two and three add to?
Which of the numbers, when multiplied by three, will come to
the total you want in each of the rows?
What do three twos add to?
How many completely different solutions can you find?
Possible extension
Learners could try this activity with other sets of three consecutive numbers.Possible support
Suggest using the interactivity or counters marked appropriately on a $3 \times 3$ square.Addition & subtraction. Combinations. Place value. Interactivities. Working systematically. Generalising. Factors and multiples. Trial and improvement. Multiplication & division. Investigations.
Published October 2003.
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NRICH is part of the family of activities in the Millennium Mathematics Project, which also includes the Plus and Motivate sites.
email: nrich@damtp.cam.ac.uk