How can I  print multiple pages on a single page via my iPhone?
Not natively, but you can with Printopia running on a Mac connected to your printer.

To do this, you need to first create a very simple Automator action. Open up Automator, and create a Print Plugin. For the Workflow, you only need to add the "Run Shell Script" action. Make sure the action is set to "Pass input: as arguments". The shell script needs only a single line:

lp -o number-up=4 -o media=Letter "$*"


The specifics of the line might depend on your needs. In this case, I'm printing to my default printer (so is't not specified). I found that without the "media" option the result was was not scaled properly. You can define number-up as either 1, 2, 4, or 16.

If you want to specify a specific printer, use the following instead:

lp -d &lt;printer&gt; -o number-up=4 -o media=Letter "$*"


where &lt;printer&gt; is one of your print queues. You can find these by executing lpstat -a at a terminal prompt.

That's it. Now save the action. I saved mine as "4-Up Print".

Next open Printopia in the System Preferences. Click the + to add a new destination, select "Add PDF Workflow", and pick the Automator Workflow that you created in the previous step.

When printing from your iOS device, pick the newly created Printopia Air Print destination. Obviously you need to be on the same local network as the Mac.

Enjoy!