Working systematically

problem
Flag-tastic

Age

11 to 14

Challenge level

How many different flags can you make?
problem
Intersection sums Sudoku

Age

7 to 16

Challenge level

A Sudoku with clues given as sums of entries.
problem
Oranges and lemons, say the bells of St Clement's

Age

11 to 14

Challenge level

Bellringers have a special way to write down the patterns they ring. Learn about these patterns and draw some of your own.
problem
Pole star Sudoku

Age

14 to 18

Challenge level

A Sudoku based on clues that give the differences between adjacent cells.
problem
Twin corresponding Sudoku

Age

11 to 18

Challenge level

This sudoku requires you to have "double vision" - two Sudoku's for the price of one
problem
Seasonal twin Sudokus

Age

11 to 16

Challenge level

This pair of linked Sudokus matches letters with numbers and hides a seasonal greeting. Can you find it?
problem
Ratio Sudoku 2

Age

11 to 16

Challenge level

A Sudoku with clues as ratios.
problem
Magnetic personality

Age

7 to 16

Challenge level

60 pieces and a challenge. What can you make and how many of the pieces can you use creating skeleton polyhedra?
problem
Integrated product Sudoku

Age

11 to 16

Challenge level

This Sudoku puzzle can be solved with the help of small clue-numbers on the border lines between pairs of neighbouring squares of the grid.
problem
Ratio Sudoku 3

Age

11 to 16

Challenge level

A Sudoku with clues as ratios or fractions.