Nothing like a viral, mind-boggling math problem to make you feel like you should have paid better attention in high school algebra.

The equation in question is a deceptively simple math problem that blew up in Japan when people found they were routinely getting the wrong answer. According to PopSugar, a study showed that only 60% of 20-somethings tackling the problem solve it correctly. So, you must be wondering now, what is this impossible equation?

## Apparently, it’s 9 – 3 ÷ 1/3 + 1 = ?

What is the remaining 40% of problem-solvers doing wrong? YouTube user MindYourDecisions shows you, bringing in mathematician Presh Talwalkar, the man behind the problem, to explain how it’s done.

The trick is to remember PEMDAS, the order of operations formula, which stands for parentheses, exponents, multiplication, division, addition, subtraction. As Talwalkar explains, this means first tackling 3 ÷ 1/3 (the answer is 9). Then, if you carry on with the equation from left to right you end up with the correct answer of—drum roll, please—1!

Unfortunately, it’s been a while for many of us (or it hasn’t, but we just didn’t pay that much attention in algebra) and most people who get it wrong actually fall down on entering the fraction into a calculator. Other people who get it wrong forget about PEMDAS, and simply do the equation from left to right.

## Common incorrect answers end up being 3, 7, or 9.

Of course, it’s just a silly math problem—or is it? According to the video, the 60% rate of correct answers is down from 90% in the 1980s. What could this big drop in accuracy suggest? Is it possible that our dependence on easy internet research and calculators means we’re committing fewer algebra principles, like PEMDAS, to memory? It’s a fascinating question. We’re going to freshen up on the quadratic equation, just in case.