When the math professor’s wife returns home from work,

she finds an envelope on the living room table.

She opens it and finds a letter from her husband:

“My dearest wife,

We have been married for nearly thirty years,

and I still love you as much as on the day I proposed.

You must realize, however,

that you are now 54 years old and no longer able to satisfy certain needs I still have.

I very much hope that you are not hurt to learn that,

while you’re reading this,

I’m in a hotel room with an 18-year-old freshman girl from my calculus class.

I’ll be home before midnight.

Your husband, who will never stop loving you.”

.
.
.

When the professor returns from the hotel shortly before midnight,

he also finds an envelope in the living room.

He opens it and reads:

“My beloved husband,

You may recall that you, too, are 54 years old and no longer able to satisfy certain needs I still have.

I thus hope that you are not hurt to learn that,

while you’re reading this,

I am in a hotel room with the 18-year-old pool boy.

Your loving wife.

P.S. As a mathematician, you are certainly aware of the fact that 18 goes into 54 many more times than 54 goes into 18. Therefore, don’t stay up and wait for me.”