or buy at Payhip or LoveCrafts This design is based on a page from a mathematical colouring book Snowflake, Seashell, Star : Colouring Adventures in Numberland by Alex Bellos and Edmund Harriss. It represents three superimposed Sudoku solutions. Numbers have been replaced by colours. The outer L-shapes show the first solution, the inner L-shapes show the second and the squares show the third. The solutions all follow normal Sudoku rules so that each colour appears only once in each row, column and block of nine squares. The design in Alex and Edmund’s book shows squares inside squares inside squares. We changed to L-shapes to make the construction easy. We used the same Sudoku solutions that Alex and Edmund used. Our shapes are striped mitred squares. The afghan is constructed in one piece. Each new square is made by picking up stitches from previous squares. We used DK yarn to make a 112 cm (45”) square to use as a wall-hanging. The pattern includes instructions for using different yarns and for changing the size. The afghan needs equal amounts of nine different colours. We used approximately 210 metres (230 yards) of each colour. There are 81 squares in the afghan. The squares are not all different. The pattern includes a version where there are 81 unique squares and another simpler version. Read the story of this afghan on Ravelry or on Woolly Thoughts web site. Both patterns contain the number grids for three different designs. The difference between the patterns is in the construction methods.