Recently, Elon Musk posted a math problem on social media platform X, stating that anyone who could solve it would be qualified to work at Tesla. This sparked extensive discussions among netizens.

The problem is an equation: 6÷2(1+2).

In the comments section, users shared their answers, but the results were polarized. Some believed the answer was "1", while others thought it was "9".

In fact, Presh Talwalkar, a Stanford University professor and mathematician, explained this problem in a video eight years ago. The main idea is to follow the left-to-right rule of operations. First, calculate the parentheses (1+2) to get 6÷2×3. Then, since multiplication and division have equal precedence, compute from left to right to get the answer 9.

However, Talwalkar also mentioned in the video that mathematical rules were slightly different in 1917. According to the old method, when encountering division, the entire left expression should be divided by the entire right expression, resulting in an answer of 1.

In conclusion, based on today’s mathematical rules, the correct answer is 9, but there is also some reasoning behind the answer being 1.