Move the matchstick on the left of 5 to its right, and you can get the correct formula, 12-9=3.

As shown in the figure below:

Extended data:

Olympic Mathematical Competition or Mathematical Olympics, or simply Olympics. 1934 and 1935, the Soviet union began to hold middle school mathematics competitions in Leningrad and Moscow, and 1959 held the first international mathematics Olympics in Bucharest.

As an international competition, the International Mathematical Olympiad was put forward by international mathematical education experts, which exceeded the level of compulsory education in various countries and was much more difficult than the college entrance examination. According to experts, only 5% of children with extraordinary intelligence are suitable for learning the Olympic Mathematics, and it is rare to reach the top of the international mathematical Olympics all the way. On August 2, 2065438+021day, Beijing took a number of measures to resolutely control the link between Olympic math scores and further studies.

Olympic Mathematics has a certain effect on teenagers' mental exercise, which can exercise their thinking and logic, and it plays a more profound role for students than ordinary mathematics.

Reference link: Baidu Encyclopedia-Olympiad Mathematics