It's posted above. You need to fill in the gaps with the digits¹ from 1 to 9 so that the equation makes sense, following the order of operations - multiply first, then division, addition and subtraction² 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 doctorate³ in economics with mathematics, but they have not given the answer."

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