Explaining, convincing and proving

  • 3 by 3 Mathdokus
    problem

    3 by 3 Mathdokus

    Age
    7 to 14
    Challenge level
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    Can you use the clues to complete these 3 by 3 Mathematical Sudokus?

  • problem

    Number Sandwiches

    Age
    7 to 14
    Challenge level
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    Can you arrange the digits 1, 1, 2, 2, 3 and 3 to make a Number Sandwich?

  • So it's times!
    problem

    So It's Times!

    Age
    7 to 14
    Challenge level
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    How will you decide which way of flipping over and/or turning the grid will give you the highest total?

  • A colourful cube made from a plastic Polydron net.
    problem

    Air Nets

    Age
    7 to 18
    Challenge level
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    Can you visualise whether these nets fold up into 3D shapes? Watch the videos each time to see if you were correct.

  • 6 by 6 Mathdokus
    problem

    6 by 6 Mathdokus

    Age
    7 to 16
    Challenge level
    filled star empty star empty star

    Can you use the clues to complete these 6 by 6 Mathematical Sudokus?

  • Calendar Capers
    problem

    Calendar Capers

    Age
    11 to 14
    Challenge level
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    Choose any three by three square of dates on a calendar page...

  • Adding all nine
    problem

    Adding All Nine

    Age
    11 to 14
    Challenge level
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    Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!

  • Winning Team
    problem

    Winning Team

    Age
    11 to 14
    Challenge level
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    Nine cross country runners compete in a team competition in which there are three matches. If you were a judge how would you decide who would win?

  • Greetings
    problem

    Greetings

    Age
    11 to 14
    Challenge level
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    From a group of any 4 students in a class of 30, each has exchanged Christmas cards with the other three. Show that some students have exchanged cards with all the other students in the class. How many such students are there?

  • Coins on a Plate
    problem

    Coins on a Plate

    Age
    11 to 14
    Challenge level
    filled star empty star empty star

    Points A, B and C are the centres of three circles, each one of which touches the other two. Prove that the perimeter of the triangle ABC is equal to the diameter of the largest circle.