2+2=5?

If you’re new here, you may want to subscribe to my RSS feed. Thanks for visiting!

Well, believe it or not, using the “math” they taught you in school, you can “prove” that is true.

Part of the math curriculum of schools is estimating, or rounding up. This is a legitimate and important concept, when it is taught by competent and interested teachers. Man, is that a big “when.”

This brings us to what is one of my main peeves about traditional math-ed. They never mention the consequences and “stuff” concerning what they are teaching you. They teach you how to estimate, and even sometimes what estimation is good for, but they never tell you the interesting stuff about it. In this case, it is the why not.

Here is why not:

If you are given, say, the problem 2.4 + 2.4 =? and you rounded before doing the equation, you’d get 2+2, which would give you the answer 4. No problem. But if you added 2.4 + 2.4 and got 4.8, and rounded after you did the equation, you’d get 2+2=5. Problem.

I am not saying that his is often a problem, or that it will screw anyone up on many tests - but it can be a problem. And, it is interesting. And I’ve never heard of a teacher mentioning this possible discrepancy.

Why not?

Using your mind to at least notice and ponder things like this keeps you sharp. It stretches and twists your imagination. Works for your brain, like it works for your muscles - keeps everything limber.

References:
http://en.wikipedia.org/wiki/Two_plus_two_make_five
This is a fascinating reference, because it illustrates meaning and math. It makes references to concepts from Orwell, Hugo, Tolstoy, et.al., which illustrate how math, reality, and belief can be twisted in malicious ways.

Tags: