The latest brain-mangling maths puzzle to hit the news is from Vietnam.

It’s posted above. You need to fill in the gaps with the digits from 1 to 9 so that the equation makes sense, following the order of operations - multiply first, then division, addition and subtraction last.

According to the VN Express, it was set as a problem for third graders in the town of Bao Loc in the Vietnamese highlands.

That’s eight year olds!

There is no complicated maths involved, only basic arithmetic. But it’s not a walk in the park.

“This problem is difficult even for adults good at math, so it will be difficult for students in grades 3, and even more challenging for students in the highlands, ” teacher Tran Phuong told VN Express.

He added: “I sent the problem for some people, including a doctorate in economics with mathematics, but they have not given the answer.”

Vietnam does very well in the international PISA tables that compare 15-year-olds’ performance in maths, science and reading. Vietnam ranks 17 in maths and 8 in science, which outperforms many Western countries like the UK (26 and 20) and US (36 and 28).

No wonder if they are given problems like this....

Can you do it?

Here is one of the solutions from a commenter at Gizmodo: There are other possible solutions, but the first one I came up with was: 6, 9, 3, 5, 2, 1, 7, 8, 4 in that order ... How I got to it was assigning each blank to a letter and writing the whole thing as an equation then grouping like terms.

So... a+13(b/c)+d+12e-f+(gh/i)-21=66.

Then you add 21 to both sides and a+d-f+13(b/c)+12e+(gh/i)=87. And since you’re limited to plugging in numbers between 1-9 for a-i, you see that there’s only so many combinations that will yield numbers close to 87. So then you start guessing and checking how large you have to make the various numbers to make it work. You need smaller numbers in the denominators and the subtraction and larger numbers being multiplied.

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