Math can be tricky sometimes — especially when a math problem appears, on the surface, to be a piece of cake. This math problem has been stumping the internet, as most people aren’t able to solve it correctly on the first try. It doesn’t help that the math rules at work here are probably long gone from your brain. This brain teaser looks like a straightforward problem, right?
Here’s the equation: 9 – 3 ÷ 1/3 + 1 = ?
While the problem doesn’t require any algebraic ‘solve for x’ equation work to recall from your distant memory, it’s not quite that simple to get the correct answer.
In fact, according to a Japanese study conducted by university researchers, only about 60% of the engineers who attempted to solve the problem were able to solve it correctly. The engineers were in their early 20s, so you’d imagine they would have still retained the basic math skills required to solve the math problem.
If you have retained the math skills, you might be familiar with PEMDAS, an acronym that means “parenthesis, exponents, multiplication, division, addition, subtraction” as a clever way to sort the order of calculation. Knowing this order of operations appears to be the key to the correct answer, but there’s a bit of a trick to it.
Many people land on 9 as the answer, but that’s incorrect.
The issue is that people forget to isolate the division part of the problem as well as tend to add, then subtract, as the order of operations would have them believe.
So how do you solve the problem? TipHero.com explains: “What you want to do here is start over by tackling 3 ÷ 1/3 first, and no, you’re not supposed to multiply here. Divide! Hint: 3 divided by 1/3 is actually 9. Take it from there. Using a calculator, it’s likely that it will read that relationship between 3 and 1/3 as a funky way to arrive at 1 before working out the rest of the equation. If you did that too, we understand how you arrived at your final answer.”
Additionally, Reader’s Digest explains: “Now, the PEMDAS rules call for you to solve all addition and subtraction problems in the order they appear. So instead of adding first, you will solve the equation from left to right.”
If you still need a visual explanation of how to solve the problem, check out the video, which pulls the division component from the middle, showing how to solve 3 ÷ 1/3, which becomes 3/1 ÷ 1/3, which equals 9.
Once you’ve solved that, you can move from left to right with the operations: 9-9+1. 9-9 is 0, add that to 1 and your answer is 1.
Among the many comments left on social media about the problem were those who didn’t find it all that challenging to solve. One person commented: “It’s simple… FRACTIONS. Division is invert. Cancel and multiply… this is done before any subtractong… so, take the middle… 3/1 divide by 1/3. this is the same a 3/1 X 3/1 which is 9. Now put this back into the equation… 9-9+1 = 1. Simple… if you remember your fractions.”
Other commenters agreed, finding it to be a “simple” problem that “even a 3rd grader can solve.”
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