Regrouping Four 10's

Date: 10/15/2001 at 19:46:26
From: Lori
Subject: Subtraction problem in Math

Hi,

I'm trying to help my nephew with this math question.

How would you regroup four 10's to find the difference between 341 
and 228?

We know the difference between 341 and 228 is 113. We don't understand 
the "regoup four 10's" part.Can you help?

Thank you!

Date: 10/15/2001 at 22:18:33
From: Doctor Peterson
Subject: Re: Subtraction problem in Math

Hi, Lori.

Regouping is what you might know as borrowing. It means that we take 
the 4 in 341, meaning 4 tens, and think of it as 3 tens and 10 ones:

      3  4  1 --->  3  3 11
    - 2  2  8     - 2  2  8
    ---------     ---------
                    1  1  3

If we were modeling 341 as 3 groups of 100 sticks, 4 groups of ten, 
and 1 single stick, this would be literally unbundling and regrouping, 
as we untied one of the 4 groups and put the ten sticks in with the 
one.

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/   

Date: 10/25/2001 at 18:47:31
From: Lori
Subject: Re: Subtraction problem in Math

Thank you so much!
This helps a great deal.