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problem
Euler's Totient Function
16 to 18
How many numbers are there less than $n$ which have no common factors with $n$?
structured_page
Impact Stories
This page details NRICH's impact through our partnership projects with schools.
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Being Curious - Secondary Teachers
These problems will tap into students' natural curiosity, enabling them to grow into creative, flexible problem-solvers.
article
Difference Dynamics Discussion
This article discusses what happens, and why, if you generate chains of sequences getting the next sequence from the differences between the adjacent terms in the sequence before it, eg (7, 2, 8, 3) maps to (5, 6, 5, 4).
problem
The Pied Piper of Hamelin
7 to 11
This problem is based on the story of the Pied Piper of Hamelin. Investigate the different numbers of people and rats there could have been if you know how many legs there are altogether!
problem
It Must Be 2000
7 to 11
Here are many ideas for you to investigate - all linked with the
number 2000.
problem
Room Doubling
7 to 11
Investigate the different ways you could split up these rooms so
that you have double the number.