Or search by topic
Each of the two main diagonals of the puzzle must have the numbers 1 to 9.
Within the 9x9 pattern there is a highlighted "rectangle" with its width four and length six cells respectively. Each width of the "rectangle" outline must contain all the four numbers 1 to 4. Similarly, each length of the "rectangle" must contain all the six numbers 1 to 6.
An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.
Place the 16 different combinations of cup/saucer in this 4 by 4 arrangement so that no row or column contains more than one cup or saucer of the same colour.
The letters of the word ABACUS have been arranged in the shape of a triangle. How many different ways can you find to read the word ABACUS from this triangular pattern?