This sub-forum is (as you can see at the top) is for "Windows/Mac Games (and Palm/Pocket PC)". We do have a sub-forum for the iOS version of this game here. Since the puzzles are the same on both versions, iOS users can find puzzle help in the Windows/Mac forum as well.

Unfortunately, the only way to pause the game on an iOS device (iPad/iPhone/iPod) would be to go to the main menu, select Options, and select "Paused". Remember to press "Done" to have the settings take effect.

It is possible to do the puzzle without pausing the game, however.