Three is always more than two
which makes sense in numbers
and in groups quite often, too.
Are two awake, one slumbers.
Or one watches out with care
while two more are sleeping.
Though this case is rather rare:
one phone is always beeping.
Numbers in pairs or blocks of three
are memorized at will.
So that for an emergency
there is no special drill.
But PINs with four digits mean trouble
when you have more than two.
Even if some appear as double
they could be difficult for you.