Please choose the correct ending to complete the given sentence: Computers and Electronics: [header] How to upgrade to windows 7 [title] Find your product key. [step] In order to save time and avoid complications, it's vital to confirm that you have a working product key; without it, trying to install windows 7 is futile. [title] Write down your computer name.

Ending1: [step] In the address bar, type in the name of your service or product key. You can even type " paint " in the search bar to see if that option is available. Ending2: [step] It's possible that your pc name will be required, so it's best to be prepared. [title] Back up your files! [step] The most common mistake is human error, so make sure your files are copied to a dvd, external hard drive or flash drive. Ending3: [step] Before installing windows 7, write down the name of your computer and your browser name, followed by a comma. This will save you space in the search results for windows 7. Ending4: [step] A good way to find it is to make a list of the installation numbers available on the terminal that you will need to install windows 7. The first of the terminal numbers is the product name in a standard operating system.

Answer format: ending1/ending2/ending3/ending4