Answer:
If we follow what we learned in school, the result will be 9, according to the principle that the calculation in parentheses is performed first 2 + 1 = 3. Then, if the calculation sequence only includes subtraction and addition or multiplication and division, it must be performed from left to right. Thus, in order 6: 2 x 3 = 3 x 3 = 9. This is the common way of calculating worldwide and is the most accurate result “today".
Why is it “today”? The controversy arises because some people use an old calculation rule, popular before 1917, that is, when using division, it is understood that the divisor is all the components on the right side of the symbol. For example: x : 2y if calculated according to this rule will be x : (2y). Thus, the result of the above calculation will be 1.