Video Transcript
Find the missing numbers by making
six equal groups from these 54 books. Six times what equals 54. 54 divided by six equals what. And 54 divided by nine equals
what.
In the picture, we can see 54
books. And they’ve been arranged in such a
way that they can help us answer this question. We’re given three number sentences,
a multiplication and two divisions. And in each number sentence,
there’s a missing number. We’re told that we need to find
these missing numbers by making six equal groups from the 54 books. Can you see how we can draw some
lines on our diagram to do this? The way that the books have been
arranged, they’re in six equal rows. This is a quick way we could find
our six equal groups. There we go, six equal groups. And there are one, two, three,
four, five, six, seven, eight, nine books in each group.
Let’s use what we can see then to
help us fill in these related facts. Six multiplied by what equals
54. In this sentence, we can think of
the number six as representing our six rows. And the number 54, that’s the
answer to our multiplication, is the total number of books that we have. So six lots of what equal 54. As we’ve already seen, there are
nine books in each row. So we can say that six times nine
equals 54. Our next number sentence is the
inverse of multiplication. We need to divide. 54 divided by six equals what. In other words, if we start with
the whole number of books, that’s 54, and we split it into six equal rows, how many
will there be in each row? The answer is going to be nine. If six lots of nine make 54, then
we can take 54 and split it up into six equal groups; there’ll be nine in each
group.
Look at how both of our number
sentences contain the numbers six, nine, and 54. Do you think our final number
sentence is part of the same family of facts? It certainly contains a 54 and a
nine, so we might expect that our missing number is going to be a six. Let’s see whether we’re right. 54 divided by nine equals what. Now, as well as this array of books
showing six rows of nine, we could also look at the books a different way and think
of them as nine columns of six. So if we divide 54 into nine equal
groups, just as we guessed, there’ll be six in each group. We’ve used this array of 54 books
to help us find three related multiplication and division facts. We know they’re in a family because
they contain the same three numbers: six times nine equals 54, 54 divided by six
equals nine, and 54 divided by nine equals six. The missing numbers are nine, nine,
and six.
