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  • Early Years Foundation Stage

Chocolate 2010

Age 14 to 16
Challenge Level Yellow star
  • Problem
  • Getting Started
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ChocolateFirst of all, pick the number of times a week that you would like to eat chocolate (try for more than once but less than 10 times as more than this is simply greedy).
Multiply this number by 2 (just to be bold).
Add 5 (for Sunday).
Multiply it by 50.
If you have already had your birthday this year add 1760.
If you haven't had your birthday yet this year add 1759.
Now subtract the four digit year that you were born.
You should have a three digit number.

The first digit of this was your original number.
The next two numbers are your age.

This problem was first published in 2010. How does this work? Does this work for any year? If not, can you adapt it so that it does?

Thanks to Jose Luis for the idea for this question.


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The nth term of a sequence is given by the formula n^3 + 11n. Find the first four terms of the sequence given by this formula and the first term of the sequence which is bigger than one million. Prove that all terms of the sequence are divisible by 6.

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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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