Internet "mystery question": 6÷2(1+2)=?
3.4 million netizens came up with two different answers to this math problem. Math teacher: The correct answer is 9 due to the concept of monomials.
"6÷2(1+2)=?" Recently, an apparently simple math problem on the internet has sparked heated discussions among countless netizens about its answer.
Reporters found online that this question was called a "mystery question," and it was claimed that more than 3.4 million netizens worldwide had attempted it, resulting in two controversial answers: 1 and 9.
**Two camps in conflict**
**Those who believe the answer is 1**
This group of netizens argues that for the expression "2(1+2)," it should be viewed as a whole from the perspective of coefficients. For example, using 3x, from the coefficient point of view, 3x is not 3·x or 3×x but represents an overall value.
Secondly, a number directly following parentheses acts as a coefficient for the content inside the parentheses rather than being part of a multiplication operation. This means each term within the parentheses (1+2) must be multiplied by 2.
"So, 2(1+2) absolutely does not equal 2×(1+2), but equals (1×2 + 2×2). Returning to the original question, 6÷2(1+2)=? Who still plans to choose 9?" one netizen remarked.
**VS**
**Those who believe the answer is 9**
However, some netizens argue that according to the rules of mixed operations involving addition, subtraction, multiplication, and division, the calculation inside the parentheses should be done first, yielding a result of 3. The remaining operations are just multiplication and division. Following the operational rules, which state that operations at the same level should be performed from left to right,
"One rule that even elementary school students know is that operations at the same level should be done from left to right." one netizen said. Thus, 6÷2(1+2) can also be interpreted as 6÷2×3, making the answer naturally 9.
**Math teacher's analysis**
2(1+2) is not a monomial; the correct answer to this question should be 9.
So what is the correct answer to this internet "mystery question"? This morning, Mr. Liu, a teacher from the Department of Mathematics at Beijing Technology and Business University, stated that according to the operational rules, one should first calculate the expression inside the parentheses, thus transforming the equation into "6 divided by 2 then multiplied by 3." According to the operational rules for same-level calculations, which proceed from left to right, the result is 9.
Mr. Liu analyzed that some people see "2(1+2)" as a single entity because middle school math textbooks mention that numbers multiplied by letters can omit the multiplication sign, and such combinations can be considered as monomials. However, there are no letters in this particular problem, so the concept of a monomial should not apply here.
Moreover, 2× and 2() are not the same concept. 2() is not a coefficient, nor does it represent a whole entity. It is simply a shorthand notation for multiplication, so each item within the parentheses cannot be multiplied individually by the number outside.
According to the operational rules, the calculation inside the parentheses should be done first, and for same-level operations, they should proceed from left to right, yielding a result of 9.
Additionally, since the latter part of this equation appears compact visually, there may be a psychological tendency to calculate it first.
"This type of calculation generally appears in elementary school, and teachers should not guide students to write equations like this. When writing equations, proper standards should be followed, and multiplication signs should be written where necessary to avoid ambiguity." Mr. Liu emphasized.
By reporter Wang Yan
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