2009 Challenge

Stage: 3, 4 and 5 Challenge Level: Challenge Level:1
You might wish to look at the most excellent Penguin Dictionary Of Curious And Interesting Numbers by David Wells to find out why other numbers are interesting.
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities can be found here.
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NRICH is part of the family of activities in the Millennium Mathematics Project.