Simultaneous equations

  • Addition Equation Sudoku
    problem

    Addition equation Sudoku

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

    You need to find the values of the stars before you can apply normal Sudoku rules.

  • Another Quadruple Clue Sudoku
    problem

    Another quadruple clue Sudoku

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

    This is a variation of sudoku which contains a set of special clue-numbers. Each set of 4 small digits stands for the numbers in the four cells of the grid adjacent to this set.

  • Colour Islands Sudoku
    problem

    Colour islands Sudoku

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

    An extra constraint means this Sudoku requires you to think in diagonals as well as horizontal and vertical lines and boxes of nine.

  • Quadruple Clue Sudoku
    problem

    Quadruple clue Sudoku

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

    Four numbers on an intersection that need to be placed in the surrounding cells. That is all you need to know to solve this sudoku.

  • All-Variables Sudoku
    problem

    All-variables Sudoku

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

    The challenge is to find the values of the variables if you are to solve this Sudoku.

  • Negatively Triangular
    problem

    Negatively triangular

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

    How many intersections do you expect from four straight lines ? Which three lines enclose a triangle with negative co-ordinates for every point ?

  • Matchless
    problem

    Matchless

    Age
    14 to 16
    Challenge level
    filled star filled star empty star
    There is a particular value of x, and a value of y to go with it, which make all five expressions equal in value, can you find that x, y pair ?
  • Intersections
    problem

    Intersections

    Age
    14 to 18
    Challenge level
    filled star empty star empty star
    Change one equation in this pair of simultaneous equations very slightly and there is a big change in the solution. Why?