Nothing.
Social Security Numbers (SSN), Preparer Tax Identification Numbers (PTIN), Employer Identification Numbers (EIN), Individual Tax Identification Numbers (ITIN), etc... are all free, you just have to meet the requirements for each.
employer
Director Identification Number is a unique identification number assigned to all existing and proposed Directors of a Company. It is mandatory for all present or proposed Directors to have a Director Identification Number. Director Identification Number never expires and a person can have only one Director Identification Number.
The model number on Samsonite luggage differs from one luggage to another. It is usually a very unique number that is used in the identification purpose.
Often businesses already have a D&B D-U-N-S® Number, which is a business's unique, 9-digit identification number, without knowing it. If not, you can register for one for free at http://www.dandb.com/.
Typically, finding out one's Taxpayer Identification Number requires one to contact the IRS. Taxpayer Identification Numbers can include Social Security Numbers, Employer Identification Numbers, and Individual Taxpayer Identification Numbers for those not registered in the Social Security system.
unique number: The number 1 has only one factor. (It is therefore unique.)
A gun with that serial number. That's as much of an answer as can be given with the information provided. Serial numbers are not unique to one firearm, and may not even be unique to one firearm in a single manufacturer's lineup.
There are several unique identifying features that humans have that distinguish one from another. These features are also know as genetic variation. Finger, arm and hand print identification marks one individual different from another. DNA sequencing and iris identification can further distinguish one person from another.
The number one has the unique property of multiplicative identity: any number times 1 is the same number.
They ae one and the same
By definition, "unique" indicates there is only one.
A number with only one unique divisor is called a "unit".
A D&B D-U-N-S® Number is a unique, 9-digit identification number for a business. Often businesses already have D&B D-U-N-S Number without knowing it. If not, you can register for a one for free at http://www.dandb.com/.