Ready for a troubling statistic? According to the official U.S. Report Card on Student Achievement, only 32% of American eighth graders are proficient in mathematics. It’s a troubling truth that reveals a lot about our curriculum and instructional missteps. After all, the U.S. *is* far, FAR behind students in other first-world countries (in fact, our math scores ranking sit at a disappointing #32).

Clearly, the way that American kiddos are learning math just isn’t adding up! So, when we hear stories of brilliant math hacks that make students’–and, let’s be honest, adults’— lives easier, we just have to share them!

Take the example of the following percentage hack. It was recently shared by Ben Stephens on Twitter and it went viral almost immediately. Let’s take a look:

Mind blown, right? As it turns out, pretty much all of Twitter was just as shocked as you are right now. Reactions ranged from amazed to incredulous to downright angry.

You see, so many of these folks were dumbfounded as to why this simple trick isn’t taught widely. It could have saved a lot of people a lot of heartache over the years. It could have made bill-splitting at restaurants and tips calculations a breeze. Just why in the HECK would the cruel math teachers of the world want to keep this from us?

Well, the answer might actually be much simpler than you’d expect. These math teachers aren’t devious people who get their kicks from withholding easy mathematical shortcuts; the truth is, many of them probably don’t know about it either! Just take a look at this math expert’s response to Stephen’s revelation:

See! This guy devoted his higher education to learning the ins and outs of super-hard mathematical equations that most of the general public will NEVER wrap their heads around, and even he had no idea that this brilliant shortcut existed!

Another commenter, who just so happens to be a former math teacher, also gushed over the hack:

But, of course, Twitter wouldn’t be Twitter without an ultra-snarky tweet. This one’s not so malicious, but it does prove that this handy hack isn’t meant to be used in all situations:

Ok, so maybe this shouldn’t be used on clunky numbers like the ones above, but it does work well in the times that you are looking for a ballpark figure, (i.e. 90% of 40).

Now that you know all about the math hack, we’d love to hear your take! Are you mad that you were never taught this in school? Do you plan on using it? Do you know of any other cool shortcuts that you would like to share?