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Topic: Teaching an old dog a new trick
Replies: 2   Last Post: Nov 14, 2017 12:29 PM

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Richard Strausz

Posts: 4,621
Registered: 12/4/04
Teaching an old dog a new trick
Posted: Nov 13, 2017 1:09 PM
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While volunteering at my neighborhood elementary school this morning, a student showed us a subtraction method for problems where the minuend (top number) has one or more zeroes. I had never seen this before. It uses the fact that 50 - 1 = 49, 300 - 1 = 299, 1000 - 1 = 999 etc.
She had us put a 'ring' around the relevant part of the minuend and then subtract. See the attached sample.


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