April Fool’s Day: Fun with Math Fallacies
2008 April 1

Photo by RBerteig.
Take a break from “serious” math and have a little fun today with some classics of recreational mathematics. Do you have a favorite math or logic fallacy? Please share it in the Comments below.
Story Problem Fallacy
- Three Men in a Hotel Room
From the comments section at Let’s play math! blog.
Algebra Fallacies
- Classic Fallacies
Can you find the false step in each of these “proofs”? - How to Double Your Salary Using an Algebraic Loophole
Another version of the beginning algebra fallacy, from WikiHow.
Geometry Fallacies
- Dissection Fallacy
63 = 64 = 65 from WolframMathWorld. - What Is Wrong? (Rouse Ball’s Fallacy)
A geometry “proof” from Cut the Knot.
Edited to Add
I found this spoof of a famous number theory joke in my feed reader this afternoon…
- Proof: all April fools’ jokes are interesting
“Let S be the set of uninteresting April fools’ jokes…”
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Have more fun on Let’s Play Math! blog:




I suppose upon using this clock, we will get younger by the seconds. Hurray! I can rectify all the major mistakes made before using back the conventional clock…
LOL! I wish it were so.