Subtraction: Learn to subtract 1-digit numbers from twenty with regrouping.
This lesson teaches how to subtract 1-digit numbers from twenty with regrouping. Practice free: http://www.ilearn.com/subtract
This playlist teaches how to subtract numbers from two digits through 4 digits. The make a ten strategy covered in the Addition and Subtraction playlist is used in these lessons to teach regrouping. http://www.ilearn.com/subtract
The playlist is organized so that students progress from the simplest cases with the smallest number of digits and no regrouping to the more difficult cases with 4-digit numbers and regrouping in more than one place.
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If you prefer to read, rather than watch this video, here’s the transcript:
Title: Learn to subtract 1-digit numbers from twenty with regrouping.
You can already subtract a one-digit number from ten.
In this lesson, you'll learn how to subtract a 1-digit number from 20, which is 2 tens.
Here's an example. 20 minus 3.
Twenty is 2 tens.
We start subtracting in the ones place.
We can't subtract 3 from 0, so we have to take a ten from 20 to make ten ones.
We cross out the 2 in 20 to show we took a ten and we put a 1 here to show we have 1 ten left in the tens place.
We put a 1 here to show that we made ten ones.
Now we subtract 3 from the 10 ones.
10 minus 3 is 7.
In the tens place there's nothing to subtract, so we bring down the 1.
That gives us 17.
So 20 minus 3 is 17.
Another example. 20 minus 8.
Twenty is 2 tens.
We start subtracting in the ones place.
We can't subtract 8 from 0, so we have to take a ten from 20 to make ten ones.
We cross out the 2 in 20 to show we took a ten and we write a 1 above it to show we have one ten left.
We show that we made ten ones by putting a 1 here.
Now we subtract 8 from the 10 ones.
10 minus 8 is 2.
There's nothing to subtract in the tens place, so we bring down the 1 we have left.
That gives us 12.
So 20 minus 8 is 12.
Last example. 20 minus 4.
We start with the ones place.
We can't subtract 4 from 0, so we have to take a ten from 20 to make ten ones.
We cross out the 2 in 20 to show we took a ten.
And we write 1 here to show there is 1 ten left, which is 10.
We put a 1 here to show that we made ten ones.
Now we subtract 4 from 10.
10 minus 4 is 6.
There's nothing to subtract in the tens place, so we bring down the 1 we have left.
That gives us 16.
So 20 minus 4 is 16.
In the rest of this lesson, you'll work problems like these. You can use these boxes if you want, but you don't have to.
http://www.ilearn.com/subtract
https://youtu.be/Y9WhHCgtE5g
