Video Transcript
Modeling Three-Digit Numbers
In this video, we will learn how to
count how many objects there are when objects are arranged in groups of 100, 10, and
one.
This is the number 358. 358 is a three-digit number. Its first digit is a three. Its second digit is a five. And its third digit is eight. The position of each digit tells us
its value. The three digit in 358 is worth
three 100s, so the three represents 300. Five is the tens digit. The five is worth 50. And the eight digit is in the ones
column. It’s worth eight ones.
But what would happen if we changed
the position of the digits? Now the eight digit is in the
hundreds place, so the eight digit is worth 800. The three digit is now worth three
10s or 30. And the five digit is worth five
ones. We made the number 835. If we change the position of the
digits, we change their value. We could model the number 835 using
place-value counters. We need eight 100s, three 10s, and
five ones. We’ve modeled the number 835.
These pencils have been grouped
together. Each box contains 100 pencils. Each pot contains 10 pencils. And this single pencil is grouped
by one. We have 100s, 10s, and ones. We need to count the total number
of pencils. We can use a number line to help us
count in 100s, 10s, and ones. We know we have two boxes which
each contain 100 pencils. So we need to count forward first
in 100s. As there are two boxes of pencils,
we need to count forward in 100s twice. 100, 200.
Next, we need to count the pots
with 10 pencils. There are three pots, so we need to
count forward in 10s three times. So we’re going to start at 200 and
count forward 10: 210, 220, 230. Now we just need to count forward
in ones: 231. We counted in 100s, 10s, and
ones. There are 231 pencils. Let’s practice counting in 100s,
10s, and ones with some questions.
Mason wants to know how many items
of fruit he bought. Answer the questions to help
him. He counts in 100s to find how many
cherries he has. Then, he counts in 10s to add the
watermelons. What three numbers should he say
after 310? 100, 200, 300, 310, what, what,
what.
In this question, we’re being asked
to count in 100s and 10s to help Mason find out how many pieces of fruit he has. The cherries come in boxes of
100. So he started to count his cherries
in 100s. 100, 200, 300. Mason also bought some watermelons,
which come in boxes of 10. So we need to start counting at 300
and keep on counting in 10s. 300, 310, 320, 330, 340. Now, we know that Mason had 340
pieces of fruit, the three numbers that he should say after 310 are 320, 330, and
340.
First, Mason counted his cherries
in 100s: 100, 200, 300. He counted his watermelons in 10s:
310, 320, 330, 340. So the missing numbers are 320,
330, and 340.
He also bought some oranges. Count on to figure out how many
pieces of fruit he has in total.
We know that Mason bought three
boxes of cherries. Each box contained 100
cherries. And he bought four boxes of melons,
and the melons came in boxes of 10. So we can start counting at
100. 100, 200, 300. We need to keep on counting in 10s
now because the watermelons came in boxes of 10. 310, 320, 330, 340. And we can count the oranges in
ones. The oranges are single pieces of
fruit. They haven’t been grouped together
in 10s or 100s. We count these as ones. 341, 342, 343, 344, 345, 346,
347. We counted in 100s, 10s, and
ones. The total number of pieces of fruit
that Mason bought is 347.
Count the marbles.
In this question, we’re shown some
different jars of marbles, these two jars of marbles both contain 100 marbles. These three jars each contain 10
marbles. These marbles haven’t been
grouped. We count these as ones. So to count the marbles, we need to
count in 100s, 10s, and ones. Let’s start counting in 100s. 100, 200. We counted in 100s twice because
there are two jars of marbles and each jar contains 100 marbles.
Next, we need to count forward in
10s because we’ve got three jars of marbles each containing 10 marbles. We’re going to start at 200 and
count forward in 10s three times. 210, 220, 230. Now what we need to do is count
forward in ones. 231, 232. We counted the marbles in 100s,
10s, and ones. There were 232 marbles.
There are 100 balls in each
bag. How many balls are there?
We can see that there are three
bags of balls. And we know that each bag contains
100 balls. So to count the number of balls in
the bags, we need to count in 100s. 100, 200, 300. But that isn’t the total number of
balls. We have to count these ones
too. They haven’t been grouped, so we
can count these as ones. There are four ones. 301, 302, 303, 304. First, we counted in 100s. Then, we counted in ones. We had three 100s and four
ones.
Did you notice that there were no
10s, only 100s and ones? The total number of balls is
304.
Count in 100s and 10s to write the
missing numbers. 100, 200, 300, what, 410, what and
what.
In this question, we’re shown some
place-value blocks. And we need to count those in
100s. 100, 200, 300, 400. We know the first missing number is
400. Now we need to continue counting in
10s: 410, 420, 430. 100, 200, 300, 400, 410, 420,
430. The missing numbers are 400, 420,
and 430.
What have we learned in this
video? We’ve learned how to count on to
find the total when objects are grouped in 100s, 10s, and ones. We’ve also learned how to model
three-digit numbers using place-value equipment.
