How to reinstall OSX Mountain Lion?

I have a 2010 iMac and currently have OSX Mountain Lion 10.8.5 installed.
I would like to reformat and erase all information from my computer but don't want to go thru starting with Snow Leopard again with the original disks that came with the iMac.
I purchased Mountain Lion thru the APP store so do not have a disk for it.
Is there an easy way for me to reinstall a fresh copy of Mountain Lion and erase all content on computer?
Thanks for helping...

Hold down Command-R during startup,
From there use disk utility to erase the drive and reinstall OS X.

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My computer is acting strangely and stops all the time to work - I can hear lots of little hard drive sounds and it is very slow until it is done (usually about 10 minutes), and my Adobe CS products are crashing and creating corrupt files that keep stopping.
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I couldn't use the installer that came with the computer because I have installed Mountain Lion since.
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No reason why not if you use the same username and password for the admin account.
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Message was edited by: tzaphon

This is not difficult and you will not have to download from the app store.
your computer has what is called a recovery partition that came with it.
simply hold cmd+R while you boot up. let go a second after you hear the chime.
you will boot into the recovery partition.
Use disk utlity to format your usb drive and then exit Disk utlity and go to Reinstall Mountain Lion.
it will ask you which disk you want to install ML onto. Choose your new USB drive.
easy peasy

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If you have a problem and need to reinstall, you don't have to pay.
OS X Recovery restores your Mac with a few clicks.
OS X: About OS X Recovery

How do i do a full reintstall of osx Mountain Lion

How do I do a full reinstall of OSX Mountain Lion so that all data from my internal hard drive on my Macbook Pro is wiped out and starting fresh?

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Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your startup volume (usually Macintosh HD) from the
      left side list. Click on the Erase tab in the DU main window.
3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on
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      the Erase button and wait until the process has completed.
4. Quit DU and return to the main menu.
Reinstall Lion/Mountain Lion, Mavericks: Select Reinstall Lion/Mountain Lion, Mavericks and click on the Install button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
            because it is three times faster than wireless.

How to reinstall OSX Mountain Lion?

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