4 x 3 = 12.Or not? This is what a girl answers in a school exercise and his teacher calls him wrong. The girl’s mother and Twitter user @Madredelalobita wanted to share her daughter’s exercise on the networks and ask users and followers why she is wrong.
A question that has sparked debate on social networks. “The order of the factors does not alter the product”is the beginning of the commutative Property, one of the most repeated principles by mathematics teachers in schools and institutes. It means that the order in which the numbers are placed in a mathematical operation such as multiplication does not matter because the result will be the same. So, why is this exercise wrong?
“I want you to try to guess why my daughter’s teacher marks this exercise as wrong,” asks a user through her networks. The tweet includes the image of a math exercise from her daughter in which the following statement is read: “There are 4 boxes with 3 rings each. How many rings are there in all?”
The girl solved the problem by multiplying 4×3=12. “There are 12 hoops”, he answered. And the teacher put a red cross on it as if it was wrong. One of the answers is that the “norm” is “content per continent”.
“I will add more fuel to the fire: If the norm is content x continent, why is there another one if it’s fine?”shows in another photograph:
Among the answers, one user explains: “The object that contains a dimension is multiplied first and then the dimension is multiplied. In the case of the rings it should have been 3*4=12 not 4*3=12, which the result is the same but not the logic”.
It also considers the possibility that since the exercise was about the multiplication table of 3, the three had to come first. Although the commutative property dictates that the order of the factors does not alter the product.
“Worse still: since the exercise is from the table of 3, the 3 has to go first. It is seen that the we leave the commutativity of the product for another day“.
The commutative property of the product
The commutative property determines that the “order of the factors does not alter the product”, that is, the same result is obtained by multiplying a b by b a (a b = b a). Both operations have the same result.