Video Transcript
Fill in the blank: one-quarter of
20 equals what.
In the picture, we can see a group
of 20 cakes. And to answer the problem, we need
to find a fraction of this quantity. We need to find one-quarter of
20. What do we know about the fraction
one-quarter? Well, firstly, the numerator is
one. This means it’s what we call a unit
fraction. In other words, we only need to
find one-quarter. We don’t need to find two-quarters
or three-quarters, only one. And the bottom number or the
denominator in one-quarter is a four. This tells us that we need to split
the whole amount into four equal parts. That’s what a quarter is; it’s one
out of four equal parts. So to find out what one-quarter of
20 is, we’re going to have to split up 20 into four equal parts.
Now, there are two ways we could do
this. Firstly, we could think about the
number 20 itself, and we could work out the answer to 20 divided by four. Or we could use the picture of the
cakes to help. We could divide this into four
equal groups. Let’s try both ways, and if we get
the same answer, we know we’ve got it right. Now there’s a quick way we can
split things into four. We start by finding a half, and
then if we find half again, that gives us four equal parts. We know that half of 20 is 10 and
then half of 10 is five. There are four fives in 20. 20 divided by four equals five. It looks like one-quarter of 20 is
five, but let’s just check using the picture.
First, we can split the group in
half. Now, if we split each half in half
by going down the middle, we can see we’re going to end up with some half cupcakes,
which we don’t really want. It makes it a bit more tricky to
count. So let’s just split each half in
half by drawing lines across. There we go. We’ve split the whole amount into
four equal groups, and there are one, two, three, four, five cupcakes in each
group. We were right. One-quarter of 20 equals five.
