Maybe you got lucky then, because when I was a kid, rote memorization was the only way teachers would accept the answer. If you changed the problem to 10 + 6 or the one op posted, the teacher would tell you that you did it wrong. This is why I just decided to do this regrouping in my head and just write what the teacher wanted because I would get the right answer anyway and not get told it was wrong.
Hmm no I’m not
Maybe you got lucky then, because when I was a kid, rote memorization was the only way teachers would accept the answer. If you changed the problem to 10 + 6 or the one op posted, the teacher would tell you that you did it wrong. This is why I just decided to do this regrouping in my head and just write what the teacher wanted because I would get the right answer anyway and not get told it was wrong.