A classic riddle is:

*Q: How many sides does a ball have?
A: Two—the inside and the outside.*

“How many sides has a tree?” was a question asked in many newspapers in 1851. “How many sides has a circle?” was printed in

*Harper’s Bazar*(New York, NY) in 1875. “How many sides does a barrel have?” was printed in many newspapers in 1964.

“How many sides does a ball have? 2 inside & outside” was posted on Twitter on April 8, 2010.

23 July 1851, Hartford (CT)

*Daily Courant*, pg. 2, col. 2:

How many sides has a tree?

Two. The inside and outside.

11 December 1875,

*Harper’s Bazar*(New York, NY), “Facetiae,” pg. 808, col. 2:

“How many sides has a circle?”

“Two,” said the student.

“What are they?”

What a laugh in the class the student’s answer produced when he said, “An inside and an outside!”

Google Books

April 1876,

*The Australian Journal*, pg. 464, col. 1:

“How many sides has a circle?”

“Two,” said the student.

“What are they?”

What a laugh in the class the student’s answer produced when he said, “An inside and an outside!”

16 November 1964, Sioux Falls (SD)

*Argus-Leader*, “Fun Time—The Riddle Box” by A. Leokum, pg. 7, cols. 7-8:

How many sides does a barrel have?

The inside and the outside.

Google Books

*Highlights Book of Science Questions that Children Ask*

By Jack Myers

New York, NY: Barnes & Noble Books

1995

Pg. 244:

How many sides does a ball have? If we should decide that it has only one, then we would say that the whole earth has only one side. That is, unless you think about the idea of inside and outside.

The Math Forum

*Does a Sphere have Sides?*

Date: 04/20/2001 at 10:18:28

From: Doctor Peterson

Subject: Re: Sides of a sphere

Hi, Sarah and Stephany.

I’d say it’s a definition question: what do you mean by “side”?

(...)

I think the most applicable definition is the one used in topology. We talk about surfaces with two sides (like a piece of paper) and surfaces with only one side (like the Moebius strip you may have heard of). In this sense, and remembering that mathematicians define a sphere as the surface of a sphere, not a solid ball, I would say that a sphere has two sides: the outside and the inside. That may sound like a joke, but it’s really the best mathematical answer I can give.

Best jokesâ€Ź

@Hultz1

how many sides does a ball have? 2 inside & outside.

6:19 PM - 8 Apr 2010

Google Books

*Trans-incidental American Adventures via the Railways*

By Erik “Skippy” Sund

Published by author

2014

Pg. 93:

He asked “How many sides does a ball have?” I answered 2. He asked “Why did you say that? What are the sides?” I replied the inside and the outside.

Reddit—Jokes

How many sides does a ball have?

submitted August 7, 2017 by TheHappinessSeeker

Two. The inside. And the outside.