Taxing a used car

[jsmoke]

Excuse my ignorance but I haven't owned a car for a while, so when buying a used car you need a 16 digit number, so you get this from the current owner or do you have to apply to DVLA, or how does it work?

 

[jsmoke]

The v5c/2 has an 11 digit number you can use online. I'm a bit concerned about what mrrockliffe said as I think the the new keepers form has been sent off a few days ago by the previous owner. I haven't picked the car up yet etc although have paid for it.