Video Transcript
Column Subtraction of Two-Digit
Numbers
In this video, we will learn how to
subtract two-digit numbers and recall the calculation using the standard written
method.
When we subtract using the column
method, we always start by subtracting the ones first. This is the ones column. The number 56 has six ones, and the
number 23 has three ones. We need to subtract three from
six. And we’ve modeled the number 56 in
our place value chart.
We can use this to help us subtract
three ones. We had six ones. We’ve subtracted three. There are three ones left. Six take away three is three. Now we need to subtract the
tens. We can see that the number 56 has
five 10s and the number 23 has two 10s. We’ve modeled our five 10s from the
number 56, and we need to subtract two of them. Five 10s subtract two 10s leaves us
with three 10s.
What is 42 take away 27?
Let’s practice what we’ve just
learned. First, we need to subtract in the
ones column. But we’ve got a problem. The number 42 has two ones. The number 27 has seven ones. Seven is greater than two. We don’t have enough ones to
subtract seven from. We need to regroup. We need to take one of our tens and
exchange it for 10 ones. Now we have three 10s and 12
ones.
Now that we’ve regrouped, we can
subtract in the ones column. We’ve got 12 ones, and we need to
take away seven. 12 subtract seven equals five. And we can write five in the ones
column. Next, we need to subtract in the
tens column. We’ve got three 10s left, and we
need to subtract two. Three 10s take away two 10s leaves
us with one 10.
So we’ve learned that when we’re
subtracting a two-digit number from a two-digit number using the column method, we
always subtract the ones first. Sometimes we need to regroup. And then we subtract the tens. Let’s put into practice what we’ve
learned by answering some questions now.
Take away 43 from 64.
In this question, we’re subtracting
a two-digit number from a two-digit number. And we’re using the column
subtraction method to calculate the answer. We’re subtracting from the number
64. We’ve drawn a quick sketch of six
10s and four ones.
First, we need to subtract in the
ones column. 64 has four ones, and 43 has three
ones. So we need to subtract three ones
from our four ones. Four take away three is one. Now we can subtract in the tens
column. 64 has six 10s, and 43 has four
10s. So we need to subtract four 10s
from six 10s. Six 10s take away four 10s leaves
us with two 10s. 64 take away 43 equals 21.
We used column subtraction to find
the answer. First, we subtracted the ones. Then, we subtracted the tens.
Take away 25 from 42.
In this question, we have to
calculate 42 subtract 25. And we can see that the question’s
been set out using column subtraction. Did you notice the orange and the
red square in the top of each column? This is a hint that we may have to
regroup before we can subtract. When we use the column subtraction
method, we always start in the ones column. 42 has two ones. And we need to subtract 25, which
has five ones.
We have a problem. We can’t do two take away five. 42 doesn’t have enough ones for us
to subtract five from. So we do need to regroup. We need to take one of our
tens. So now we have three 10s in the
number 42. And instead of having two ones,
we’ve got 12.
Now that we have enough ones, we
can subtract in the ones column. What is 12 subtract five? It’s seven. Now we can subtract in the tens
column. We’ve got three 10s, and we need to
take away two 10s. Three take away two is one. We’ve got one 10 left. One 10 and seven ones gives us an
answer of 17. 42 take away 25 equals 17.
Before we could subtract in the
ones column, we had to regroup. Then, we were able to subtract the
ones and then the tens. 42 take away 25 is 17.
Find the value of the following: 26
subtract 15.
In this question, we have to
subtract a two-digit number from a two-digit number using column subtraction. When we use the column method, we
always subtract the ones first. The number 26 has six ones, and 15
has five ones. We need to subtract five from
six. What is six take away five? It’s one. So we can write a one in the ones
column. We had six ones. We subtracted five. We’ve got one left.
Now we can subtract in the tens
column. We know the number 26 has two 10s
and the number 15 has one 10. So we need to subtract our one 10
from our two 10s. What is two 10s take away one
10? It’s one 10. So 26 take away 15 is 11.
First, we subtracted the ones. Then, we subtracted the tens. 26 take away 15 equals 11.
Find the value of the following: 34
subtract 15.
In this question, we’re subtracting
a two-digit number from a two-digit number using the column subtraction method. We need to start by subtracting in
the ones column. 34 has four ones, and 15 has five
ones. So we need to calculate four
subtract five. At the moment, we don’t have enough
ones to subtract our five from. We’re going to need to regroup. We need to take one of our
tens. So now we’ve got two 10s instead of
three. And we can add 10 ones into the
ones column. Instead of having four ones, we’ve
got 14 ones. What is 14 take away five? It’s nine. So we can write this in the ones
column.
Next, we need to subtract the
tens. Two 10s take away one 10 leaves us
with one 10. 34 subtract 15 equals 19. We found the answer using column
subtraction.
What have we learned in this
video? We’ve learned how to subtract
two-digit numbers using column subtraction.
