How can I continue a partial, interrupted download of Yosemite? I was trying to download OS X Yosemite. It is very big - more than 5GB.

The download did not succeed due to some problem in internet connection. Only 2.5 GB is downloaded and I wanted to continue from where it stopped. I closed the Mac App Store and reopened. I lost what was downloaded till that time. I want to know where it is stored in my Mac so that I could start from there. It saves me lot of time and internet download usage, since it is a limited internet plan.
It is stored in the Application folder - if it doesn't continue, then delete the already downloaded file, and retry from the App Store again.