Video Transcript
Subtracting by Adding with Numbers
up to 10
In this video, we’re going to learn
how to solve subtraction problems by finding the missing part in an addition
expression with numbers up to 10. To find 10 take away six, we can
use addition. This part–whole model shows the
number 10 which we can call the whole amount. One way to find 10 take away six,
we could think about which number we need to add to six to make 10. In other words, if 10 is the whole
amount and six is one of the parts, what would the other part be?
This 10 frame shows six
counters. How many more counters do we need
to add to make 10? How many counters do we need to add
until the 10 frame is full? One, two. Now we have eight, three, four. Six and four are a pair of numbers
which go together to make 10. So we know that if six plus four
makes 10, 10 take away six is four. We could also solve 10 take away
six using our number track. To find out what we need to add to
six to make 10, we just need to start at number six and count forward until we reach
number 10. One, two, three, four.
We’ve learned that addition and
subtraction are related. We know that six and four is 10,
and four plus six equals 10. And knowing that these two numbers
are a pair which make 10 helps us to find related subtraction facts. 10 take away six equals four and 10
take away four equals six. Let’s practice solving subtraction
problems now by finding the missing part in an addition sentence with numbers up to
10.
Complete: seven subtract three
equals what. You can use the following addition
sentence to help you. Three plus what equals seven.
In this question, we have to find
seven take away three, and we’re given a partial addition sentence to help. Three plus something equals
seven. We know the whole amount is seven,
and we know that one of the parts is three. So to help us find seven take away
three, we can think about the number that we need to add to three to make seven. We could use a 10 frame and some
counters. We’ve got three counters. How many more do we need to add to
make seven? One, two, three, four. Three and four are a pair of
numbers which makes seven. If three plus four equals seven,
then seven take away three equals four. The missing number is four. Seven take away three equals
four.
Liam had nine toy cars. He lost three of the cars. He can work out how many are left
by completing either of the following number sentences. Nine take away three equals
what. Three plus what equals nine. How many cars are left?
This is a subtraction problem. We know that Liam had nine toy cars
and he lost three of them. We have to work out how many cars
he has left. This part–whole model helps us
think about how to solve the problem. We know the whole amount or the
number of cars Liam had to begin with is nine. We know that one of the parts or
one of the numbers that go together to make nine is the number three because Liam
lost three of the cars. So one way we could find out how
many cars Liam has left is to subtract the three that he lost from the nine he had
to begin with.
This is where the 10 frame becomes
really useful. There are nine cars in the 10
frame, and three of them have been crossed out because we know that Liam lost three
of his cars. How many cars are there left? In other words, what is nine take
away three? It’s six. There are six cars left in the 10
frame, so we know that three and six are the two numbers that go together to make
nine. If nine take away three is six,
then three plus six equals nine because three and six are a pair of numbers which go
together to make nine. If Liam had nine toy cars and he
lost three of them, he has six cars left.
Chloe and Daniel made six
cupcakes. After their dog ate some, there
were two left. They want to know how many cupcakes
their dog ate. Who is correct? Chloe says: We can solve two plus
what equals six. Daniel says: We can solve six take
away two equals what.
We know that Chloe and Daniel had
six cupcakes to begin with. We can model this using six
counters in a 10 frame. We also know that after their dog
ate some, there were two cupcakes left, so we know that one of the parts in our
part–whole model is the number two. They had six cupcakes. Their dog ate some. And they have two left. Chloe says we can solve two plus
what equals six. If we know that two plus four makes
six, Chloe must be correct. And if we look at our 10 frame, we
can see that there are two counters and four counters have been crossed out, but
there are six counters altogether. Two and four are a pair of numbers
which go together to make six. So Chloe is correct.
Daniel said we could solve six take
away two. He’s also correct. If two plus four equals six and six
take away two equals four, addition and subtraction are related. So if Chloe and Daniel made six
cupcakes, their dog ate some, and they had two left, they can work out how many
cupcakes their dog ate by either solving two plus four equals six or six take away
two equals four. They’re both correct.
What have we learned in this
video? We have learned how to solve
subtraction problems by finding the missing part in an addition sentence.