Odd and even numbers

  • Impossible Sandwiches
    article

    Impossible sandwiches

    In this 7-sandwich: 7 1 3 1 6 4 3 5 7 2 4 6 2 5 there are 7 numbers between the 7s, 6 between the 6s etc. The article shows which values of n can make n-sandwiches and which cannot.
  • All is Number
    article

    All is number

    Read all about Pythagoras' mathematical discoveries in this article written for students.

  • Take one example
    article

    Take one example

    This article introduces the idea of generic proof for younger children and illustrates how one example can offer a proof of a general result through unpacking its underlying structure.
  • Summats Clear
    problem

    Summats clear

    Age
    16 to 18
    Challenge level
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    Find the sum, f(n), of the first n terms of the sequence: 0, 1, 1, 2, 2, 3, 3........p, p, p +1, p + 1,..... Prove that f(a + b) - f(a - b) = ab.
  • Arrangements
    problem

    Arrangements

    Age
    7 to 11
    Challenge level
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    Is it possible to place 2 counters on the 3 by 3 grid so that there is an even number of counters in every row and every column? How about if you have 3 counters or 4 counters or....?
  • Score
    problem

    Score

    Age
    11 to 14
    Challenge level
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    There are exactly 3 ways to add 4 odd numbers to get 10. Find all the ways of adding 8 odd numbers to get 20. To be sure of getting all the solutions you will need to be systematic. What about a total of 15 with 6 odd numbers?
  • Great Granddad
    problem

    Great Granddad

    Age
    11 to 14
    Challenge level
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    Great Granddad is very proud of his telegram from the Queen congratulating him on his hundredth birthday and he has friends who are even older than he is... When was he born?