If there are three pieces of cheese
in a box, how many pieces are there in seven boxes?
Nowhere in this word problem does
it tell us what we need to do to find the answer. So how do we know what we need to
do? Well, first of all, we could look
at the problem and ask ourselves what we need to find out. And that’s the number of pieces of
cheese there are in seven boxes. And the problem tells us one more
piece of information that will help us find the answer. And that’s that each box contains
three pieces of cheese. To help us understand how to use
this information we’ve been given, we could sketch a bar model.
There are three pieces of cheese in
a box so we could draw a small bar and label it three. And so, to show how many pieces
there are in seven boxes, we can draw seven small bars and label them all with the
number three. And we can see now what we need to
do to find the answer. We need to find seven lots of
three. This is a multiplication problem,
isn’t it? And to solve it, we’re going to
have to find the answer to seven times three. Let’s remind ourselves of our three
times table facts.
One times three is three, two
threes are six, three times three is nine, four threes are 12, five times three is
15, six threes are 18, and seven threes are 21. And so, we know that if there are
three pieces of cheese in a box, the number of pieces that there will be in seven
boxes will be the answer to seven times three. The answer is 21 pieces.