[aninhumer]

The purpose of marking a test is to communicate to the child whether they understand the topic. Marking an almost correct answer wrong (without elaboration) is bad feedback.

The problem that people are raising here isn't how the child feels, it's how the child thinks. And one thing they might think as a result of this answer is "Oh, I guess multiplication isn't the same both ways. I must have been mistaken." and it might take some time for this misunderstanding to clear up.