Yes, but that works great when doing it on the spot in your head, and not so on paper where you have the benefit of writing down the steps of ( non-core ) arithmetic algorithms.
Common core breaks down when you have to involve writing down the steps due to the size of the operands and there ordinary algorithms shine.
No it doesn't break down. The point of common core is to help students understand why. The how is important but learning the rote algorithms are as helpful for understanding as using a calculator.
If they wrote $5.55, they deserve the full credit. I do arithmetic admittedly weirdly in my head. I can't do arithmetic very quickly.
When faced with $20 - $14.45, I round up the $14.45 to $15 and subtract from $20. I have $5. Now, I think how much more I still have and that is $0.55. I add them together to get $5.55.
If I can write the answer, why would you dock points just because my way of doing this simple math is inefficient?
Because the answer doesn't matter. If you just need the answer you can use a calculator. The point is to help kids develop an intuition for how numbers work.
The way you described calculating change is essentially the method taught in common core.
Common core is not about efficiency, it's about helping kids develop an intuitive understanding of how numbers work.
It turns out that a lot of children who learned how to subtract on paper with borrowing never learn how to do math in their head the way you described. Common core is an attempt to correct that deficiency.
Are you addressing me specifically? Hn does not give me the option to downvote direct replies to my comments, even if I wanted to. Someone else on this website felt your comment deserved a downvote.
HN does not permit one to downvote direct replies to one's own comments, however, even if it did, I don't see how a downvote has any bearing on the merit of one's argument.
Common core breaks down when you have to involve writing down the steps due to the size of the operands and there ordinary algorithms shine.