Working systematically

  • Small tomato seedlings in pink pots.
    problem

    Magic Error

    Age
    11 to 14
    Challenge level

    Two of the numbers in a 4×4 magic square have been swapped. Can you work out the sum of these numbers?

  • Small tomato seedlings in pink pots.
    problem

    Subtracting to 2008

    Age
    11 to 14
    Challenge level

    Can you work out the sum of the missing digits in this subtraction?

  • Small pepper seedlings in turquoise pots.
    problem

    Isometric Rhombuses

    Age
    11 to 14
    Challenge level

    Weekly Problem 31 - 2016
    The diagram shows a grid of $16$ identical equilateral triangles. How many rhombuses are there made up of two adjacent small triangles?

  • Small tomato seedlings in yellow pots.
    problem

    Half and Half

    Age
    11 to 14
    Challenge level

    Two of the four small triangles are to be painted black. In how many ways can this be done?

  • Small tomato seedlings in pink pots.
    problem

    Multiplication Table Puzzle

    Age
    11 to 14
    Challenge level

    In the multiplication table on the right, only some of the numbers have been given. What is the value of A+B+C+D+E?

  • Master Minding
    problem

    Master Minding

    Age
    11 to 14
    Challenge level

    Your partner chooses two beads and places them side by side behind a screen. What is the minimum number of guesses you would need to be sure of guessing the two beads and their positions?

  • Pattern of islands
    problem

    Pattern of Islands

    Age
    11 to 14
    Challenge level

    In how many distinct ways can six islands be joined by bridges so that each island can be reached from every other island...

  • Small tomato seedlings in pink pots.
    problem

    So Many Sums

    Age
    11 to 14
    Challenge level

    In this addition each letter stands for a different digit, with S standing for 3. What is the value of YxO?

  • Small pepper seedlings in turquoise pots.
    problem

    Blockupied

    Age
    11 to 14
    Challenge level

    A 1×2×3 block is placed on an 8×8 board and rolled several times.... How many squares has it occupied altogether?

  • Small tomato seedlings in pink pots.
    problem

    Even Squares

    Age
    11 to 14
    Challenge level

    Can you find squares within a number grid whose entries add up to an even total?

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