I have taken off a plastic disk which is on the wall above the front door on the inside of the apartment, its cover the hole for installing an alarm system.
I took the cover to the paint shop on the corner near the post office and we found the exact match for the hall, lounge and bedroom walls.
The match was so good it made painting the walls difficult because you could not see where you were up to!!!
When you put the cover back you just paint over it.
The cream colour in my apartment is code F7 07 85 I thing it was from the ProColor range, 43 euros for 10 litre enough for 1 coat of all the walls in a 2 bedroom apartment. My ceilings are white.