Stage: 2 Challenge Level: 
Starting with the number $180$, take away $9$ again and again, joining up the dots as you go.
Watch out - don't join all the dots!
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Trial and improvement. Visualising. Compound transformations. Factors and multiples. Multiplication & division. Addition & subtraction. Working systematically. Practical Activity. Games. Interactivities.
Published February 2002.
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