my karbonn s2 has 512 MB RAM but it is always shows 85 % full I have installed RAM cleaner app but not happy with it. sometimes my phone hang down. what can be done to increase the memory (RAM) ?
I am guessing you are not considering adding more physical RAM to your phone, because it is not possibly at least not safely!
You could try and remove applications you dont use, many of them have background services running.
Disable live wallpapers if any!
Root your phone and remove all bloatware.
Install a light launcher on your phone and see how that works out!
Link for rooting instructions : Root