He works it out with a pencil.
A grafight.
Sits down and works it out with a pencil.
He derives!
He calls it a work of art.
Because they got sin and cos to give them a tan.
They get a pencil and work it out.
He worked it out with a pencil.
He grabs a pencil and tries to work it out
A: A nasty smell that you can't get rid of.
Seriously, it is not a joke. I really want to know.