Video Transcript
What number is missing? Four, what, six, seven. We’re given a picture that
shows a sequence of numbers. We can see these numbers shown
as digits, four, six, and then seven. And underneath, we can see the
same sequence shown in blocks, four blocks, six blocks, and seven blocks. But our sequence isn’t all it
seems. There’s a missing number. If we count through the
sequence, we can see four, then a big gap where our missing number belongs, and
then six and seven. And the question asks us, what
number is missing? In other words, what comes
after four in our sequence?
We’re given three possible
answers to choose from. And we can see those over
here. And if we look at these answers
quickly, we can see which number is missing. But let’s work it out for
ourselves. The only two numbers that are
next door to each other that we know already are six and seven. And we know that if we count
forwards in ones, we count from six to seven. Seven is the number that comes
after six. And so, we know that our
missing number must be the number that comes after four when we’re counting in
ones. One, two, three, four. What comes next? Five, our missing number must
be the number five.
But if we look at our three
possible answers, we can see that each one of them shows the digit five. How can we decide which one is
correct? Well, we need to count the
blocks underneath. We need to show five blocks to
match our digit five. Let’s count each group of
blocks. In the first group, we have
one, two blocks. This doesn’t show the number
five at all. Let’s try our second possible
answer. In this one, we have one, two,
three, only four blocks. Again, this is too small.
It looks like our last answer
must be the correct one. Let’s just count to make sure
that there are five blocks. One, two, three, four, five
blocks. Now, we think we’ve found our
missing number. Let’s see whether our sequence
makes sense. Four, five, six, seven. We’ve counted forwards in ones
and we’ve found that our missing number was the number five. The correct answer is the one
that shows the digit five and also five blocks underneath.
