### 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?

# Quadruple Sudoku

By Henry Kwok

#### Rules of Quadruple Sudoku

This is a variation of sudoku on a standard 9x9 grid. The object of the puzzle is to fill in the whole 9x9 grid with numbers 1 through 9 (one number per cell) so that each row, each column, and each of the nine 3x3 boxes contains all the nine different numbers 1 through 9.

The clues are in the form of sets of four special clue-numbers. Each set of four numbers can be foundat the intersection of two grid lines and they are the numbers in the four adjacent grid cell.

##### How the special clue numbers work:
Each set of four cells around four clue numbers overlaps an adjacent set of four cells around a separate set of clue numbers. The shared or overlapping cell must contain a digit that is in both of the small sets.

For example, the two sets ofsmall digits {1678} and {1249} in the top lefthand box of the grid both referencethe cell (2,2). This cell must therefore contain the digit 1 as it is the only digit common to the two sets of special clue numbers.