### Consecutive Numbers

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

### Tea Cups

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.

### Counting on Letters

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?

# Colour Islands Sudoku 2

By Henry Kwok

### Rules of Colour Islands Sudoku

As in a standard Sudoku, the object of the puzzle is to fill in the whole 9x9 grid with numbers 1 through 9 so that each row, each column, and each of the nine 3x3 boxes must contain all the nine different numbers 1 through 9.

There are three coloured "islands" in the 9x9 grid. Within each 'island' there is an extra rule to apply:
• EVERY group of nine cells that form a 3x3 square within each 'island' must contain the numbers 1 through 9.
For example, take the cell r6c8 which contains the number 9 as the centre of a 3x3 square within the pink 'island'. The eight surrounding cells (r5c7, r5c8, r5c9, r6c7, r6c9, r7c7, r7c8 and r7c9) must contain all the remaining eight digits.