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Cherries Come in Twos

Age 7 to 11
Challenge Level Yellow starYellow star
  • Problem
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Abigail from Histon and Impington Infants School sent a very clear solution to this problem:

I used some counters to represent the cherries. I did what Suzie did and worked out that if you started with $4$ cherries, you would end up with $1$ left after doing pair, pair, single. If you started with $8$ cherries, you would end up with $2$. If you started with $12$, you would end up with $3$, and if you started with $16$, you would end up with $4$.
I spotted that the end numbers went up by one each time, and the start numbers went up by four. Then I did a table:

Table of results for Cherries Come in Two's!
Start End
4 1
8 2
12 3
16 4
20 5
24 6
28 7
32 8
36 9
40 10
44 11
48 12
52 13
56 14

So there were $56$ cherries in the bowl at the start.

Well reasoned, Abigail.


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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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