Counting

  • Euromaths
    problem

    Euromaths

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

    How many ways can you write the word EUROMATHS by starting at the top left hand corner and taking the next letter by stepping one step down or one step to the right in a 5×5 array?

  • Cube Paths
    problem

    Cube Paths

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

    Given a 2 by 2 by 2 skeletal cube with one route 'down' the cube. How many routes are there from A to B?

  • Pairs
    problem

    Pairs

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

    Ann thought of 5 numbers and told Bob all the sums that could be made by adding the numbers in pairs. The list of sums is 6, 7, 8, 8, 9, 9, 10,10, 11, 12. Help Bob to find out which numbers Ann was thinking of.

  • Back to the Planet of Vuvv
    problem

    Back to the Planet of Vuvv

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

    There are two forms of counting on Vuvv - Zios count in base 3 and Zepts count in base 7. Can you work out in which direction the Zios and Zepts were looking, based on the information you're given?

  • Cinema Costs
    problem

    Cinema Costs

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

    Weekly Problem 41 - 2009
    At a cinema a child's ticket costs £4.20 and an adult's ticket costs £7.70. How much did it cost this group of adults and children to see a film?

  • FEMTO
    game

    Femto

    Age
    14 to 16
    Challenge level
    filled star filled star filled star

    A new card game for two players.

  • FEMTO: Follow up
    game

    Femto: Follow Up

    Age
    14 to 16
    Challenge level
    filled star filled star filled star

    Follow-up to the February Game Rules of FEMTO.

  • Voting Paradox
    problem

    Voting Paradox

    Age
    14 to 18
    Challenge level
    filled star filled star empty star

    Some relationships are transitive, such as 'if A>B and B>C then it follows that A>C', but some are not. In a voting system, if A beats B and B beats C should we expect A to beat C?

  • Ruler
    problem

    Ruler

    Age
    16 to 18
    Challenge level
    filled star empty star empty star

    The interval 0 - 1 is marked into halves, quarters, eighths ... etc. Vertical lines are drawn at these points, heights depending on positions. What happens as this process goes on indefinitely?

  • Links and Knots
    article

    Links and Knots

    Some puzzles requiring no knowledge of knot theory, just a careful inspection of the patterns. A glimpse of the classification of knots, prime knots, crossing numbers and knot arithmetic.