Originally Posted by squishys
No, the correct answer was supposed to be 3x10=30. I thought the same as my son, so I don't understand how it is wrong.

Perhaps it's the commutative property problem again. My best guess: the answer book says 3x10=30. If the teacher doesn't understand the commutative property fully, she may be insecure about marking 10x3=30 correct.

You could think of an innocent way to ask her why 10x3 is wrong.