At first glance, it looks easy. But it’s stumped many over the years.
Similar problems have gone viral on social media, highlighting the apparent lack of knowledge of basic arithmetic.
The solution harkens back to an acronym some likely learned in school: BODMAS, or brackets, open; divide; multiply; add; and subtract, in that order.
It’s also known as PEMDAS, or parentheses first, exponents (ie powers and square roots) next, multiplication and division (left-to-right), and addition and subtraction (left-to-right).
In this case, it means that one will have to solve (12 ÷ 4 + 1), which is 4.
Then one has to move on to the multiplication operation, which is 1 x 4, followed by 15 – 4.
The answer is 11.
This problem went viral in Japan after a recent study found only 60 percent of people between the ages of 21 and 29 could get the correct answer–down from 90 percent in the 1980s.
Despite appearing simple, Presh Talwalker of Mind Your Decisions noted what had fooled most people.
“You should write an expression that groups one third as one group,” he says in the video.
“Three divided by one third is equal to nine, and now we have nine minus nine, plus one,” he added
It follows the same PEMDAS or BODMAS rule.
Are Americans Bad at Math?
It’s been noted that Americans aren’t great at math compared to other developed countries.
“Americans continually score either in the mid- or bottom-tier when it comes to math and science compared to their international peers,” says BigThink. “Students have a fundamental misunderstanding of what math is and what it can do. By viewing it as a language, students and teachers can begin to conceptualize it in easier and more practical ways.”
It says that Americans worry too much about “rote memorization,” and students have a difficult time learning the concepts in sequential order.
“Unlike the more difficult and comprehensive math tests given to test students’ comprehension, this test was for basic numeracy skills. The United States fell behind in 22nd place,” it says.