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Well done to everybody who had a go at this activity. We only had a couple of solutions sent in, so please email us if you have any more ideas about how to solve these triangles.

Penny from Hillbrook Primary School in the UK sent in this solution:

Good ideas, Penny! I wonder why it's easier if you pair the big numbers with the small numbers, and put the medium numbers together? 

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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.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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