The 4 digit on “feature” does knock the security down quite a lot. However, all keys not in the access code are connected to the same point so you could increase your security by using a pad ...

A five-digit number generally known as a ZIP code is important in making sure your package is delivered; it identifies a certain postal delivery area in the United States. There is also another ...

How to Divide a Matrix in MATLAB. ... A UPC code consists of a 1-digit number, a 5-digit manufacturer's code, a 5-digit product code, and a single check digit.