Why do this problem?
requires only simple adding, but also persistence and logical thinking.
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?
Learners could try this activity with other sets of three consecutive numbers.
Suggest using the interactivity or counters marked appropriately on a $3 \times 3$ square.