Stage: 2 Challenge Level: 
What do the digits in the number fifteen add up to?
How many other numbers have digits with the same total if we only include numbers without zeros?
Addition & subtraction. Place value. Combinations. Visualising. Interactivities. Factors and multiples. Trial and improvement. Working systematically. Investigations. Multiplication & division.
Published September 2002,July 2009,August 2009.
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