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Shedding Some Light

Age 7 to 11
Challenge Level Yellow star
  • Problem
  • Student Solutions

Gurjeet from Cranford Community College says:


There are 6 straight lines and 5 lights on each 6*5= 30 so there are 30

Eleanor sent in her solution to the rest of the problem:

I guessed that there were about 25 lights in the picture. When I counted them there were 28, but I think there are some that you can't see behind the metal bits. My guess was quite a good one because it was only 3 away from the real number that you can see in the picture. It looks like there are 6 rods, and if they all have the same number of lights then the total should be 30, so I think there are two more lights that are hidden. The shape in the middle is a pentagon, but one of the rods doesn't fit in with the rest.

Thank you Eleanor and Gurjeet!




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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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