Does anyone know if there's a way to determine the age of an HP 4000
via the serial number?

I know that some companies use a numbering scheme that easily lets you
figure out the approximate "born on" date.

Any help appreciated...

Look at the label under the top cover. Along with the serial number
is the Date of Manufacture. Unless you need the exact time it was
made, the Month and Year are shown on the label.

Raymond