All credit and debit cards have a serial number printed on them. These numbers are unique for all cards and reveals some information about the card. This number is not generated at random but follow a simple arithmetic.
I found this little problem circulating via e-mail and social networks, why we get an error while renaming or creating any file/folder with "CON", "PRN", "AUX" etc names. This is absolutely true and here is the correct explanation and some more keywords.
IMEI (International Mobile Equipment Identity) number is a unique number associated with every mobile phone as its identity. There is an interesting maths theory behind each IMEI number. Its last digit is computed according to Luhn Algorithm. Before 2003 this check digit was always set to 0. After revision of GSMA guidelines it has changed.
Gmail doesn't recognize dots (.) as characters within a username. Google Ignores "." in Google Account Username At A Time Of Login and Also At Time Of Creating New Account. This way, you can add and remove dots to your username and change your email id. May be some of you do not believe, but this is a very interesting Fact. Read full story here...