Meaning: a number that is one more than three; a symbol of this number, 4 or IV or IIII.
The palm orientation faces towards the signer for the cardinal number (dollar, number, year). Except for the exclamation.
But, the palm faces towards the listener when telling age, o'clock, etc.
This cartoon reminds me of a heartbreaking story told by a woman in the video Unveiled Audism.
The woman came to a class and observed. When the teacher wrote on the board "2+2", the kid excitedly replied "4" in ASL. The teacher shook his/her head, "No, wrong! Say it using voice!"
There are also stories in this similar vein where deaf kids were forbidden from using sign language.
Contributed by ASLwrite.