## 8. Math Jokes

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.