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This is a classic brain teaser I learned in middle school (or “junior high school” where I grew up).

Let’s prove that:

$2 = 1$

Â Here’s the proof:

Let’s start by establishing some variables:

$a = 1$

$b = 1$

Okay, so if that’s true, then we know:

$a = b$

Â In algebra, we learned we could multiply both sides of the equation, so:

$a \times a = b \times a$

or

$a^2 = b a$

Â And of course, we can also subtract a number from both sides of the equation:

Â $a^2 - b^2 = ba - b^2$

Now, we can factor that equation to get:

Â $(a + b)(a - b) = b(a - b)$

Of course, $(a - b)$ cancels out, so:

Â Â $(a + b) = b$

Putting back in the numbers, we see that:

Â  $(1 + 1) = 1$

Â or

Â  $2 = 1$

And there is our proof!

To misquote Groucho Marx:

“An eighth grader could understand that! Someone fetch me an eighth grader!”