I present here the longest and shortest math jokes I know. Furthermore, I will render the long one unfunny by explaining it.

Here goes:

One day, \(e^x\) sees \(x^2\) running down the street in a panic.

“What’s wrong?”, asks \(e^x\).

“There’s a Differential Operator in town!”, yells \(x^2\). “If I run into him too many times, I’ll disappear!”

“Don’t worry,” responds \(e^x\). “I’ll go have a chat with him. No, don’t worry about me – he can’t hurt me. After all, I’m \(e^x\).”

So, \(e^x\) walks down the street to the Differential Operator.

“My friend tells me you’re a Differential Operator”, \(e^x\) says pompously. “Well, I’m \(e^x\)!”

“Pleased to meet you, \(e^x\),” says the Differential Operator. “I’m \(d/dt\).”

And here’s my favourite math joke:

Let \(\epsilon < 0\).

Here’s the punch line for the long joke explained: every time you differentiate a power, like \(x^2\), its exponent decreases by one; eventually (after two more differentiations in our case), it turns into a constant, which, after one more differentiation, becomes \(0\); when you differentiate the exponential, \(e^x\), it doesn’t change; this explains why \(x^2\) was afraid of the Differential Operator, while \(e^x\) was not; the punch line is that the Differential Operator was \(d/dt\), so it’s differentiating with respect to a different variable, and \(e^x\) is effectively a constant, and will disappear after one differentiation.

I’d love to see some other math jokes in the comments.