Turn on the laptop and find the size of the installed RAM on your computer. Click on start on the bottom left corner of the screen, then right click on 'My Computer and select properties. It will display the size of the installed RAM in a popup menu.
The second limiting factor is the operating software installed on the laptop, as every operating system has a limit to the capacity of memory it can support.
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Purchase the required RAM from a computer store and make sure they are seal packed. The clock frequency of the new RAM should be matched with the already installed RAM or else it will give rise to compatibility issues. Turn off the laptop and remove its battery.
Use a screw driver to remove the screws that hold the entire memory compartment in its place. Generally there are four slots in the compartment, install the new RAM in their place and press them tight till you hear a snap sound. Repeat the same step for any other RAM you wish to install. Put the compartment back in its place with the screws.
Turn on the laptop and verify whether the new memory has been recognized by the system or not.