Stage: 2 Challenge Level: 
Why do this problem?
This
activity involves not too difficult calculations but a lot of
thought is needed to decide what numbers they should put
together.
Possible approach
Key questions
What order do you want to work things out?
Possible extension
Possible support
Trial and improvement. Combinations. Investigations. Working systematically. Factors and multiples. Addition & subtraction. Time. Estimating and approximating. Generalising. Multiplication & division.
Published September 2001.
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