Anonymous wrote:

Decomposing 201 to subtract it from 300 is an EXCELLENT strategy for subtraction, in that case.

201 is just 200, and a 1. Take away the 200 first, now you have 100 left. Now take away the 1 to get 99.

Much better than the "algorithm" where you cross out a bunch of 0s and borrow from the next column over.

It isn't an overly complicated strategy, at all. I agree that forcing kids to use overly complicated strategies is very bad -- but I am really not sure that you understand what is overly complicated, and what isn't.

I think the example wasn't saying someone should write down 300-201 and cross out numbers. I think the point was that this is the type of problem that you use mental calculation and just answer. Once a child has the foundation of traditional math, they quickly see the relationships between the numbers.

Writing out ...201 is just 200, and a 1. Take away the 200 first, now you have 100 left. Now take away the 1 to get 99..is overly complicated.


If someone asks you to say the word number you say "number". You don't write out the phonics and syllables for them and then say number.

You don't write all the out. I am describing the thought process. It is very quick in real time.

And no, children who learn how to subtract by starting in the right hand column, and saying 0 minus 1, you can't do that, so go here, oh it is a 0, go to the 3.... cross out the 3...." do NOT necessarily quickly see the relationship between numbers. Because they don't HAVE to in order to use the algorithm. That's why people teach the algorithms... so kids can get the right answer without necessarily understanding what they are doing.

And when they get a completely wrong answer, like off by an order of magnitude, they do not recognize how wrong they are.

My favorite example is the 4th grader who couldn't remember the algorithm and added 46 + 27 and got 613. NO CLUE that it didn't make sense as an answer.