as a math person, I appreciate common core's attempt to teach high level math to 1st graders, but it was written by people who don't understand math in the slightest
instead of using basic algorithms (like that weird long division thing we all learned back in the day), they figure it's not about "can you get the right answer" and more about "do you understand the intrinsic nature of algebra and number theory, and still get the right answer without understanding what the hell you are doing?"