### Polydron

This activity investigates how you might make squares and pentominoes from Polydron.

### Eight Dominoes

Using the 8 dominoes make a square where each of the columns and rows adds up to 8

### Prime Magic

Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?

# A Cartesian Puzzle

##### Stage: 2 Challenge Level:

Here are the coordinates of some quadrilaterals, but in each case one coordinate is missing!  The coordinates are given going round each quadrilateral in an anti-clockwise direction.
1. $(2,11), \; (0,9),\; (2,7),\; (?,?)$
2. $(3,7),\; (3,4),\; (8,4),\; (?,?)$
3. $(18,3),\; (16,5), \;(8,5),\; (?,?)$
4. $(13,12),\; (15,14),\; (12,17),\; (?,?)$
5. $(7,14),\; (6,11),\; (7,8),\; (?,?)$
6. $(15,9),\; (19,9),\; (16,11),\; (?,?)$
7. $(11,3),\; (15,2),\; (16,6),\; (?,?)$
8. $(9,16),\; (2,9),\; (9,2),\; (?,?)$

The quadrilaterals are all symmetrical. This may be rotational or line symmetry or both. Can you work out what the missing coordinates are if you know they are all positive? Is there more than one way to find out?

Now plot those eight missing coordinates on a graph like this. What shape do they make and what sort of symmetry does it have?

{Please note that this activity was slightly adjusted on the 18th June 2015, thanks to a comment we received}