# Zoomable Number Line

**Click** on number line to zoom in, **shift-click** to zoom out.

Click at left or right to scroll.

## Learn About Numbers

See that numbers behave the same, whether they are 1, 2, 3, or 10, 20, 30, or 0.01, 0.02, 0.03.

Learn about decimals:

- Zoom in and look at: 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, ...
- Then ask: what is 0.9 + 0.1 ?

Do the same after zooming in further:

- What is 0.09 + 0.01?
- What is 0.19 + 0.01?
- What is 0.99 + 0.01?

You can see how decimal place values work and get a feel for "infinite" sub-divisibility (but this tool gets into trouble around 30 decimal places).

## Using

**Click** on number line to zoom in, **shift-click** to zoom out. It will zoom from where you click.

Click at left or right to scroll.

Or you can use your keyboard's arrow keys. |

Try this:

- Use the "right" key, you will see the counting numbers whizz past.
- Stop when you reach 100.
- Go back to zero (press the reset button).
- Zoom in to show 0.1, 0.2, 0.3, ...
- Now try tracking right. The tenths whizz by.
- How long does it take to reach 100 now?
- Try zooming in to 0.01, 0.02, 0.03, ...
- How long does it take to track across to 100 now (if you have the patience!) ?

How much better to realise that you can zoom out a level and go up in tens. Then you can zoom in so that you are at 100.00

Test yourself. Start at 0. Use the zoom and left/right to find these numbers:

- 3.4
- 17.85
- −17.85
- 100.00357

## Race To 100.00357

Challenge your friends! Start at 0 (press the '0' button), then see how fast you can get to 100.00357 (you must see that number on the screen).

## Least Moves

How many moves does it take to find a number?

Not against the clock but by counting the number of moves you make.

Use just the arrow keys and try to find the (Note: A count of your keystrokes is in the bottom corner.) |

How many moves does it take you to reach:

**3.4**(it took me 7 moves)**22.45**(it took me 18 moves)**100.00357**(it took me 51 moves)