Okay, so I've got a Samsung Galaxy Mini (GT-S5570), with an 180MB internal storage and 16 GB sdcard. I started installing some apps, but had to uninstall them since they did not work properly. These apps weren't from Google Play, and I'd downloaded them from the net. The thing which I realised with quite a few apps was that when I installed it, if I had 100 MB remaining; after uninstalling, it left me with only 98.6 MB or something like that. This problem happened with the apps downloaded from the net, and I think it also happened with a few apps from the Market. I can't afford to have this memory being depleted, so can someone tell me why this is happening and how can I fix it? Thanks a LOT! 
PS I don't want to factory reset.
PS I don't want to factory reset.