Q&A #6281

Teachers' Lounge Discussion: Addition/subtraction

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From: loyd

To: Teacher2Teacher Public Discussion
Date: 2001111620:06:47
Subject: Regroup or Borrow

Nowadays, we usually hear "regroup" in subtraction in lieu of
"borrow."  I guess borrow is an old fashioned word.  I was taught by
the borrowing method (about 1939) working from right-to-left (borrow,
subtract; borrow, subtract).  But many students I tutor regroup from
left-to-right.  After they finish the entire regrouping process, they
begin their subtraction. 

I don't dictate the method to the kids I tutor, if they know what they
are doing.  

Problem is, the subtraction regrouping process is often not understood
by many of the students I tutor and many of them use the modern
left-to-right process which I suppose is mathematically correct.  Many
students mark up the problem so severe, I can't see what the original
problem is and neither can they.  

If anyone is interested I prepared a PowerPoint (jpg) picture and
posted it on my small web site that shows both methods.  Comments are


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