Video Transcript
In multiplying by two, each row is
two more than the previous one. One times two equals two. Two times two equals four. Three times two equals six. Complete the following: Four times
two equals what. And then, complete the following:
Five times two equals what.
In maths, there are often patterns
everywhere we look. And in questions like this, we can
use the patterns that we find that help us find the answers. Perhaps one of the best sentences
we could ever say in maths is “I don’t know the answer, but I do know this fact, and
I’m going to use it to help.” And in a way, this is what this
question is all about, using facts that we already know to help us find facts that
we don’t.
Our first sentence tells us about a
pattern. In multiplying by two, each row is
two more than the previous one. In the model, we can see some rows
of cubes. And each cube has a value of
two. We can see the number two written
on them. The first row shows one lot of
two. And of course, we know one times
two equals two. But then, look what happens in our
second row. We’ve taken the answer from before,
and we’ve added one more lot of two, the yellow cube on the end. We now have two lots of two. And two times two equals four.
The pattern continues with our
third row. This is made up of the answer from
before and then two more. We know from the last fact that two
times two equals four. So, if we find two more than this,
we get the answer six. And that’s how we know three times
two equals six. Now, we’ve got some times tables
facts to complete. Perhaps you know the answers
already. But in case you don’t, let’s
continue using this method.
We’ll use facts that we already
know, and we’ll build on them. So, the first fact we need to find
is four times two. And if we look at our row of cubes,
we can see that there are three red cubes. We know where these are from, don’t
we? These are the three cubes that made
up the answer to the last fact. And just like all our other facts,
we’ve got a new cube on the end. These are the two more that we need
to add.
We know from our last fact that
three times two is six. So, to find four times two, we
simply need to add another two. We need to find two more than
six. And six plus another two is eight,
so four times two must equal eight.
In the last part of the question,
we need to find five times two. So, we can do the same thing
again. Take the answer from the last
question, which is eight, and then add another two. Eight add two equals 10. And so, we know five times two
equals 10. Even though we may not have known
all the multiplication facts in this question, we took the facts we did know and we
used them to help. If we know what three times two is,
we simply add two to find four times two. And if we know what four times two
is, we do the same again to find five times two. Four times two equals eight. And five times two is 10. Our two missing numbers are eight
and 10.
