Not Subtracting

Baca Juga

I love how Twitter works some days. OK, most days. #MTBoSfanboy

I retweet Scott's video talking about multiplication with his daughter. (He has lots of nice videos along these lines.)

 Martin responds with a connection.

 Brad shares the video.

 I respond, prompting a (as usually, intriguing) Dan tweet. Which will double as the moral of this blogpost.

/Explaining/ a trick is good math!

Which Marilyn responds to... (talk about fanboy). And we will be looking into this trick.

Cool stuff in Nicholas' trick shared by Ms. Burns.

Links: Scott's post with his video, Brad's video, Marilyn's blog with her trick.

Since this wound up here, I thought I'd share how I subtract.

When I was in 2nd grade, Mrs. Schultz told us you can check subtraction by adding the result back. 6 year old mathchico thinks that if this is always correct, why don't we do that in the first place?

132 - 49? 3 plus 9 is 12 so 1+4 (now I'd say ten + forty) is 5, and 8 plus 5 is 13. Done, 83.

Over the years I've gotten in a lot of trouble for not borrowing.

One more:

 6+5=11.

 8+(6+1)=15

 7+(4+1)=12

 2+1=3.

Solved and checked, Mrs. Schultz!

Peace be to any teacher who had me in class, up to and including my advisor, Nigel Higson.






And Dan writes my signoff: