Stage: 2 Challenge Level: 
Why do this problem?
This problem is not for the faint hearted! It requires logical thinking and perseverance. Learners who enjoyed this problem may like to try Single Track .Key questions
How could you start?
How will you remember what you have tried?
Remember that the engine can push and pull.
Perhaps using some counters will help?
Addition & subtraction. Investigations. Combinations. Compound transformations. Interactivities. Tangram. Visualising. Working systematically. Practical Activity. Multiplication & division.
Published July 1999.
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