Video Transcript
Column Addition of Three-Digit
numbers: Regroup Tens
In this video, we will learn how to
add three-digit numbers when we have to regroup tens and record the calculation
using column addition.
When we’re adding three-digit
numbers using column addition, we need to use our knowledge of place value. Three-digit numbers have a hundreds
digit, a tens digit, and a ones digit. We start adding in the ones
column. Then, we have the tens in the tens
column. Then, we add in the hundreds
column. Do you know why we always start
adding in the ones column? We do this in case we need to
regroup. The greatest number of ones we can
have in the ones column is nine. When we have 10 ones, we have to
regroup. We have to exchange our 10 ones for
one 10. The greatest number of tens we can
have in the tens column is also nine. When we have 10 tens, we have to
regroup. We exchange our 10 tens for
100. In this video, we’re going to be
learning how to regroup in the tens column.
In this example, we have to use
column addition to add together 271 and 354. We’ve modeled our calculation using
a place value chart and some place value blocks. We always start adding in the ones
column. We need to add together one and
four, which gives us a total of five ones. Now, we need to add the tens. 271 has seven tens, and 354 has
five tens. So, we need to add together seven
tens and five tens. Seven and five is 12. But this is not how we write
it. Once we have 10 tens, we need to
regroup. And we know that 12 is more than
10. We need to regroup 10 of our tens
and exchange them for 100.
Now, we can write the remaining two
tens. We need to exchange our 10 tens for
100 and write a one in the hundreds column because 10 tens equal 100. We had 12 tens. Now, we have two. We exchanged 10 tens for 100. Now, when we’re adding in the
hundreds column, we can add our two hundreds and three hundreds, which gives us a
total of five. And then, we need to add the one we
exchanged. Five and one more is six. So, 271 plus 354 is 625. We had a total of 12 tens. We regrouped and exchanged 10 of
our tens for 100.
Let’s practice adding three-digit
numbers where we have to regroup the tens using some questions.
Use place value blocks to show how
to add 342 and 183.
In this question, we have to use
column addition to add together 342 and 183. And the question tells us to use
place value blocks to help. When we use column addition to add
together two three-digit numbers, we always start adding in the ones column, 342 has
two ones and 183 has three ones. So, we need to add together two and
three. Two ones and three ones gives us a
total of five ones. We need to make sure to write the
five in the correct column; we need to write it in the ones column. 342 has four tens and 183 has eight
tens. So, we need to add together four
tens and eight tens. Four and eight is 12. We need to regroup some of our
tens. 10 tens make 100. So, we can exchange 10 tens for
100.
Now we have two tens, which we can
write in the tens place. And we need to add 100 into the
hundreds column because we exchanged 10 tens for 100. And we need to remember to add this
100 when we’re adding in the hundreds column. 342 has three hundreds; 183 has
100. We know that three plus one is
four. Now, we just need to add the 100 we
exchanged. Four plus one gives us a total of
five hundreds. 342 plus 183 is 525.
We used column addition to add
together 342 and 183 to give us our total of 525. We used the place value blocks to
help.
Find the sum. 275 plus 331.
In this question, we’re asked to
find the sum of 275 and 331. Sum is another way of saying
total. This is the total we get when we
add together two or more numbers. We can see from the way the
question’s been set out that we need to use column addition. Let’s start by adding in the ones
column. We need to add together five and
one; five and one is six. Next, we need to add the tens. We’ve got seven tens and three
tens. Seven plus three is 10. 10 tens are 100. So, we can write one in the
hundreds column because we’re exchanging 10 tens for 100. And we need to write a zero in the
tens column. 10 tens are 100. So, we have 100 and no tens. Now, we just need to add the
hundreds. Two plus three is five plus the one
we exchanged is six. The sum of 275 and 331 is 606.
First, we added in the ones column,
then the tens column. There were 10 tens. We exchanged these 10 tens for 100,
and then we added the hundreds column. 275 plus 331 is 606.
Find the following: 376 plus
243.
In this question, we’re being asked
to use column addition to help add together two three-digit numbers, 376 plus
243. It helps to set our calculation out
on squared paper. We can use the squares to help us
make sure we write each digit in the correct column. First, we add the ones; we’ve got
six and three. Six ones and three ones gives us a
total of nine ones. Next, we need to add the tens. 376 has seven tens, 243 has four
tens. So, we need to add together seven
and four. Seven and four makes 11. We can write one in the tens place,
and we need to exchange the other 10 tens for 100.
Finally, we need to add the
hundreds. Three plus two is five plus the one
we exchanged gives us a total of six. Nine ones, 11 tens, we exchanged 10
tens for 100, we had five hundreds, then we had to add the one we’d exchanged to
give us a total of six hundreds. 376 plus 243 gives us a total of
619.
We added together our two
three-digit numbers, starting in the ones column. Next, we added the tens column. Because we had 11 tens, we had to
regroup. We exchanged 10 tens for 100. And finally, we added the
hundreds. 376 plus 243 is 619.
What have we learned in this
video? We’ve learned how to add
three-digit numbers using column addition. We’ve also learned how to regroup
the tens. And we’ve learned that we can
exchange 10 tens for 100.
