Video Transcript
More or Less: One, 10, or 100
In this video, we will learn how to
use place value to help us add or subtract one, 10, or 100 from a three-digit
number. This is a three-digit number. Do you know which number this
is? It’s the number 584. And we can see that this number has
three digits. The five digit is in the hundreds
place, so this digit is worth five 100s. We could model the value of this
digit using place value equipment. Let’s model the five digit in the
number 584 using some place value counters. Here’s 100, two, three, four, five,
100, 200, 300, 400, 500. So the five digit is worth 500.
The next digit in this number is an
eight. The eight is in the tens place. It’s worth eight 10s. Let’s model this with eight 10s
counters. Eight 10s make 80: 10, 20, 30, 40,
50, 60, 70, 80. So the eight digit is worth 80 and
the ones digit is a four. So we need four ones counters, one,
two, three, four. The four digit is worth four. Five 100s, eight 10s, and four ones
makes the three-digit number 584.
In this video, we’re going to learn
how to add one, 10, or 100 to a three-digit number and how to subtract one, 10, or
100 from a three-digit number. This is when our place value
counters become really useful. If we were to add one to this
number, we would just need to add another ones counter into the ones column. There we go. Now we have five 100s, eight 10s,
and five ones. One more than 584 is 585. Adding one to a number is also the
same as counting forward by one: 584, 585. What would happen if we were to add
10 to the number 585? Instead of having eight 10s, the
number would have nine 10s. The tens digit has increased by
one. When we’re adding 10 to a number,
it’s the same as counting forward 10 on a number line: 585, 595.
What would happen if we added
another 10 to our number? Instead of having nine 10s, we’d
have 10. But that can’t be right. We can only write one digit in each
place. We need to exchange our 10 10s for
100. 10 10s are equal to 100: 10, 20,
30, 40, 50, 60, 70, 80, 90, 100. Now we have no 10s and six
100s. 10 more than 595 is 605. If we add 100, we’ll have seven
100s. One more than six 100s is seven
100s. The hundreds digit has increased by
one. Adding 100 is the same as counting
forward by 100 on a number line: 605, 705. To find one less than a number, we
just need to take away one from the ones place or count back in ones: 705, 704.
How would we find 10 less than
704? There are no 10s in the tens
place. We need to exchange. We need to take one of our 100s
counters and exchange it for 10 10s. Now we can take away a 10. If we have 10 10s and we take away
one 10, we’ll have nine 10s left. 10 less than 704 is 694. To find the number which is 100
less than 694, we just need to take 100 from the hundreds place. We’ve got six 100s, and if we take
100, we’ll have five left. 100 less than 694 is 594. The hundreds digit has decreased by
one. Finding 100 less than a number is
the same as counting back by 100. Let’s practice now finding one, 10,
or 100 more or less than a three-digit number using place value equipment to
help.
Olivia uses place value blocks to
show a number. What is the number? What is 100 less than this
number?
Olivia has modeled a three-digit
number using place value blocks. The first thing we have to do is
work out what the number is. Three-digit numbers have a hundreds
digit, a tens digit, and a ones digit. Let’s start by counting the number
of 100s in this number. How many 100s blocks can you count
in the hundreds place? There are three. Let’s count the number of 10s
blocks now. There’re five. How many ones can you count? One, two, three, four, five, six,
seven. Olivia’s number has three 100s,
five 10s, and seven ones. Olivia has modeled the number
357.
In the second part of the question,
we have to find the number that is 100 less than this number. To find 100 less than 357, we need
to take away one of the 100s blocks. We have three 100s, and if we take
away 100, we’ll have two 100s left. We still have five 10s, and we
still have seven ones. Two 100s, five 10s, and seven ones
is 257. To find 100 less than 357, we took
away one of the 100s blocks. 100 less than 357 is 257.
What is one less than 277?
277 is a three-digit number. The two digit is worth two 100s,
this seven digit is worth seven 10s, and this seven is worth seven ones. We need to find one less than this
number, so we just need to take away a one. If we have seven ones and we take
one away, there will be six ones. The ones digit has decreased by
one. One less than 277 is 276.
Find the number which is 10 less
than 181.
The number 181 is a three-digit
number. The first digit is a one. It’s worth 100. The eight digit is worth eight 10s:
10, 20, 30, 40, 50, 60, 70, 80. Eight 10s are worth 80. And the final digit or the third
digit is worth a one. And we know that one one is
one. We have to find the number which is
10 less than 181. To find 10 less than our number, we
just need to take away a 10s counter. Eight 10s take away one 10 leaves
us with seven 10s. The tens digit has decreased by
one. Now we have one 100, seven 10s, and
a one. 10 less than 181 is 171. To find 10 less, we took a 10s
counter away from the tens place. 10 less than 181 is 171.
Find the number that is 100 more
than 852.
We could use a place value chart to
help us find 100 more than 852. 852 has eight 100s, five 10s, and
two ones. To find 100 more than this number,
we need to add 100. Our number has eight 100s, and if
we add one more 100, we will have nine 100s. The hundreds digit has increased by
one. The number that is 100 more than
852 is 952.
What is 10 less than 207?
We can use a place value chart and
some place value counters to help us model the number 207. What do you notice about this
number? It has two 100s, no 10s, and seven
ones. To find 10 less than 207, we need
to take away a 10. But how can we do that if we don’t
have any 10s in the tens place? We’re going to need to
exchange. We can take 100 from the hundreds
place and exchange it for 10 10s. Now we have one 100 and 10 10s. And to find 10 less, we need to
take away one of our 10s. 10 10s take away one 10 leaves us
with nine 10s. Now, our three-digit number has one
100, nine 10s, and seven ones. 10 less than 207 is 197.
What have we learned in this
video? We’ve learned how to find one, 10,
or 100 more or less than a three-digit number using place value equipment.
