# Number - March 2007, Stage 3&4

## Problems

### Triangle Numbers

##### Stage: 3 Challenge Level:

Take a look at the multiplication square. The first eleven triangle numbers have been identified. Can you see a pattern? Does the pattern continue?

### Cunning Card Trick

##### Stage: 3 Challenge Level:

Delight your friends with this cunning trick! Can you explain how it works?

### Route to Infinity

##### Stage: 3 and 4 Challenge Level:

Can you describe this route to infinity? Where will the arrows take you next?

### Twizzles Venture Forth

##### Stage: 4 Challenge Level:

Where we follow twizzles to places that no number has been before.

### Twizzle Arithmetic

##### Stage: 4 Challenge Level:

Arrow arithmetic, but with a twist.

### Twizzle Wind Up

##### Stage: 4 Challenge Level:

A loopy exploration of z^2+1=0 (z squared plus one) with an eye on winding numbers. Try not to get dizzy!

### Twizzle Twists

##### Stage: 4 Challenge Level:

Make the twizzle twist on its spot and so work out the hidden link.