Stage: 3 Challenge Level: 
If you wrote all the possible four digit numbers made by using each
of the digits 2, 4, 5, 7 once, what would they add up to?
Permutations. Generalising. Divisibility. Mathematical reasoning & proof. Working systematically. Multiplication & division. Factors and multiples. Visualising. Workshop. Addition & subtraction.
Published July 2002,August 2002.
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