Funny Math Proofs

We hope you enjoy our collection of funny math proofs, favorite math jokes and jokes about numbers. You may want to check out our algebra math jokes, calculus math jokes, geometry math jokes etc. on our Math Trivia page.

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A collection of Funny (or Flawed) Math Proofs

A Mathematical Proof that "Girls are Evil"

1. “Girls require time and money”;

girls = time × money

2. “Time is money”:

time = money

3. So girls are money squared:

girls = money²

4. ”Money is the root of all evil”:

money =

5. So, girls are evil:

The above proof is incorrect because "Money is not the root of all evil". It is "The love of money that is the root of all evil" and of course "girls are not evil" (Proof by Majority Rule).

Prove that 2 = 1

If a = b (so I say)                                        [a = b]
And we multiply both sides by a
Then we'll see that a²                                  [a² = ab]
When with ab compared
Are the same. Remove b². OK?                 [a²− b² = ab − b²]

Both sides we will factorize. See?
Now each side contains a − b. [(a+b)(a − b) = b(a − b)]
We'll divide through by a
Minus b and olé
a + b = b. Oh whoopee! [a + b = b]

But since I said a = b
b + b = b you'll agree? [b + b = b]
So if b = 1
Then this sum I have done [1 + 1 = 1]
Proves that 2 = 1. Q.E.D.

Written by PeterW

(Just in case you're wondering - the above proof is incorrect because in step 5, we divided by (a - b) which is 0 since a = b)

$1 = 100 cents
= (10 cents)²
= ($0.1)²
= $0.01
= 1c

The above proof is incorrect because 100 cents = 10² cents ≠(10 cents)²

A Proof that 0 = 1

The above proof is incorrect because when we take the square root we must be careful to include both the positive and negative roots. There should then be two possible answers (one of which is to be rejected).