CUDA installation error of unmet dependencies

I was trying to install CUDA and got this error:

$ sudo apt-get install cuda
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 cuda : Depends: cuda-6-5 (= 6.5-14) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

On searching, a lot of folks had this error. Their errors were solved when they removed old NVIDIA packages they had installed. But, I did not have any NVIDIA package installed!

What were these broken packages I had on the system, I didn’t know! I followed the dependency chain by trying to install cuda-6-5, which complained on another package and so on. In the end, I found that I had a lot of unnecessary packages, all of which had :i386 at the end of their name.

The strangest part was that running sudo apt-get autoremove had no effect on these packages, they were not removed. So, I manually removed all of them using sudo apt-get remove.

When I tried to install CUDA after this, it worked fine! 😊

Tried with: Ubuntu 14.04