Subtraction Done Two Ways

I am continuing my blog series on common core math problems explained.  Today’s blog focuses on subtraction done two ways.

The first way that we will discuss is the method that parents are most familiar with which is subtraction with borrowing or regrouping.  An example can be seen here:

This is the method that makes most sense to most parents because it is how we were taught.  In this example a ten is borrowed from 84 and added to the 4 to become 14.  The problem becomes solvable from here.

Common core subtraction is entirely different from subtraction with borrowing or regrouping.  The following is an example of it:

With a problem like 62 minus 14 you start with the 14.  You then figure out what you need to add to get to 20 which is the closest ten.  This answer is 6.  You keep adding tens until you reach the top number in the tens place (60).  You then add ones to make the whole number (62).  You then add together the column of tens and ones (6+10+10+10+10+2) to get your answer.

I personally prefer subtraction with regrouping because I think that the common core way requires too many steps.  However, many schools are teaching common core.  Hopefully this brief tutorial will help clarify the process for both methods.

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