Video Transcript
What number is missing from the
table?
The table that we’re given in this
question has two rows. And each of the rows contains a
series of numbers, well, almost all of the rows. Can you see this last part of the
table has a missing number? And when our question asked “What
number is missing from a table?”, it’s this number that we’re looking for. Now, often with a table, we might
have a series of labels for each column or maybe each row to show us what
information they contain. But there aren’t any labels
here. How do we know where all these
numbers are coming from? Well, we need to be really careful
with this table because it would be very easy to make a mistake.
If we try reading the numbers
across the table — 16, 20, 24, 32 — we might think to ourselves that could be a
pattern, especially if we look at the numbers in the bottom row four, five, six, and
then our missing number. If we don’t really think it
through, it would be very easy to write the number seven here. Four, five, six, seven. It looks like a pattern. But if there’s one thing we can
learn from a question like this, it’s to read it really carefully. Something we haven’t mentioned is
that, on the left-hand side of the table, we can see an operation divided by
four. And if we read each column of the
table from top to bottom, this explains how it works. It’s almost like a dividing
machine.
We start with the number on the
top; in the first column, that’s 16. We then divide it by four, and the
answer is the number on the bottom row. We know that 16 divided by four is
four. And that’s why the number four is
on the bottom row. And we can see that the other
numbers in the table are being divided by four too. 20 divided by four equals five. We know this, don’t we, because
five times four is 20, and 24 divided by four equals six. And again, we know a times tables
fact that can help us with this; six times four is 24. And so we know that to find our
missing number, we need to take the top number 32 and divide it by four. We could use our knowledge of times
tables facts to help here.
What do we multiply four by to give
us the answer 32? Well, as we’ve just said, six fours
are 24, so we could start counting from there. Seven fours are 28 and eight fours
are 32. This is the fact that’s going to
help us here. If we know that there are eight
lots of four in 32, if we start with 32 and divide it by four, the answer is going
to be eight. It’s a good job we didn’t write
seven, isn’t it? There isn’t a pattern in the bottom
numbers of this table. We had to find out the answer not
by looking for a pattern, but by dividing the top number by four. 32 divided by four equals
eight. And so the missing number is
eight.
