
It's just FOUR digits.
The month and day.
The Big Bang Theory Season 9, Episode 9

Three. Four.
The Big Bang Theory Season 8, Episode 19

And I carried it, had to
stay in bed for FOUR months,
The Big Bang Theory Season 11, Episode 16

Four keys!
The Big Bang Theory Season 7, Episode 24

- Four dozen should suffice.
- Four dozen?
The Big Bang Theory Season 1, Episode 4