Video Transcript
Arrange 77613970, 718701545,
392434430, and 762816353 in descending order.
When we arrange something in
descending order, this means we start with the largest and we get smaller and
smaller. It’s the order from largest to
smallest. Now, if we read our question, we
can see that we have four different numbers. Each of the numbers has at least
eight digits. Three of them have nine. And there are commas within each
number and also separating the numbers. So, if we look quickly at the
question, it might just look like a string of digits. How can we compare these numbers
and put them in order?
Well, a good way for us to do this
is by writing the numbers vertically, and we can use a place value grid to help us
do this. The largest of these numbers, as
we’ve already said, has nine digits. So, we need to make sure that our
place value grid has nine columns. The lowest value of these columns
is the ones column. To the left of that we know is the
tens column, then the hundreds column. We can call the hundreds, tens, and
ones our ones section. The next three columns we can call
our thousands section. We have the thousands column, ten
thousands column, and hundred thousands column. And our final group of three digits
are the millions. We have the millions column, tens
of millions, and hundred millions.
Now, we’ve created our place value
grid. Let’s write each number vertically
in there. 77 million, 613 thousand, 970. Onto our second number, 718
million, 701 thousand, 545. Our third number is 392 million,
434 thousand, 430. And the last of our four numbers is
762 million, 816 thousand, 353. Now, as we’ve said already, to
arrange these numbers in descending order, we need to look for the largest number
first. And so, the column we need to be
looking at is the hundred millions column. It’s the column with the largest
value. Which number has the largest value
digit in this column? Well, we can see, two numbers have
the largest digit. They both have seven. We can’t split them up.
So, now we need to move on and
compare the digit with the next largest value, and that’s the tens of millions
digit. In the first of our two numbers
that we’re looking at, there’s one lot of ten million. But in the second of our two
numbers, there are six lots of ten million. And six is greater than one. And so, we can say that the last
number on our list should actually be the first number if we’re writing the numbers
in descending order. It’s the largest of the four
numbers. So, let’s begin by writing out that
number, 762816353.
Now that we’ve worked out the
largest number, the other three numbers are very straightforward to put into
order. We know that the second largest
number must be the number we were just looking at, 718701545. We know this because it’s the other
number that has 700 million in it. And out of our two remaining
numbers, it’s easy to see which is largest.
The first number that we’re looking
at doesn’t have any hundred millions. In fact, it’s an eight-digit
number, not a nine-digit number. And so, we know the larger of the
two numbers must be 392434430. And so, the first number in our
original list is actually the last number if we put the numbers in descending
order. It’s the smallest number. And so, if we arrange these numbers
in descending order, the order is 762816353, 718701545, 392434430, and finally
77613970.
