WEBVTT
00:00:02.210 --> 00:00:04.430
Modeling Three-Digit Numbers
00:00:06.000 --> 00:00:16.270
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.
00:00:17.830 --> 00:00:20.730
This is the number 358.
00:00:21.820 --> 00:00:24.610
358 is a three-digit number.
00:00:25.820 --> 00:00:28.000
Its first digit is a three.
00:00:28.910 --> 00:00:31.420
Its second digit is a five.
00:00:32.440 --> 00:00:34.770
And its third digit is eight.
00:00:35.850 --> 00:00:39.860
The position of each digit tells us its value.
00:00:41.020 --> 00:00:50.580
The three digit in 358 is worth three 100s, so the three represents 300.
00:00:51.780 --> 00:00:54.170
Five is the tens digit.
00:00:55.190 --> 00:00:57.660
The five is worth 50.
00:00:58.530 --> 00:01:01.150
And the eight digit is in the ones column.
00:01:01.380 --> 00:01:03.200
It’s worth eight ones.
00:01:04.360 --> 00:01:08.510
But what would happen if we changed the position of the digits?
00:01:09.890 --> 00:01:17.050
Now the eight digit is in the hundreds place, so the eight digit is worth 800.
00:01:18.090 --> 00:01:22.060
The three digit is now worth three 10s or 30.
00:01:23.070 --> 00:01:26.590
And the five digit is worth five ones.
00:01:27.170 --> 00:01:30.810
We made the number 835.
00:01:31.830 --> 00:01:37.060
If we change the position of the digits, we change their value.
00:01:38.470 --> 00:01:43.760
We could model the number 835 using place-value counters.
00:01:45.070 --> 00:01:52.820
We need eight 100s, three 10s, and five ones.
00:01:53.680 --> 00:01:57.530
We’ve modeled the number 835.
00:01:58.870 --> 00:02:01.780
These pencils have been grouped together.
00:02:02.880 --> 00:02:06.420
Each box contains 100 pencils.
00:02:07.420 --> 00:02:10.900
Each pot contains 10 pencils.
00:02:12.200 --> 00:02:15.780
And this single pencil is grouped by one.
00:02:17.300 --> 00:02:21.160
We have 100s, 10s, and ones.
00:02:22.060 --> 00:02:25.170
We need to count the total number of pencils.
00:02:25.960 --> 00:02:31.950
We can use a number line to help us count in 100s, 10s, and ones.
00:02:32.680 --> 00:02:37.870
We know we have two boxes which each contain 100 pencils.
00:02:38.410 --> 00:02:41.850
So we need to count forward first in 100s.
00:02:42.670 --> 00:02:48.260
As there are two boxes of pencils, we need to count forward in 100s twice.
00:02:49.330 --> 00:02:52.730
100, 200.
00:02:53.730 --> 00:02:56.950
Next, we need to count the pots with 10 pencils.
00:02:57.800 --> 00:03:03.150
There are three pots, so we need to count forward in 10s three times.
00:03:04.060 --> 00:03:15.230
So we’re going to start at 200 and count forward 10: 210, 220, 230.
00:03:16.960 --> 00:03:22.080
Now we just need to count forward in ones: 231.
00:03:23.150 --> 00:03:26.870
We counted in 100s, 10s, and ones.
00:03:28.100 --> 00:03:31.670
There are 231 pencils.
00:03:33.620 --> 00:03:38.760
Let’s practice counting in 100s, 10s, and ones with some questions.
00:03:41.360 --> 00:03:45.390
Mason wants to know how many items of fruit he bought.
00:03:46.390 --> 00:03:48.790
Answer the questions to help him.
00:03:50.080 --> 00:03:54.210
He counts in 100s to find how many cherries he has.
00:03:55.300 --> 00:03:59.050
Then, he counts in 10s to add the watermelons.
00:04:00.060 --> 00:04:04.680
What three numbers should he say after 310?
00:04:05.620 --> 00:04:15.100
100, 200, 300, 310, what, what, what.
00:04:16.390 --> 00:04:26.100
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.
00:04:27.740 --> 00:04:30.600
The cherries come in boxes of 100.
00:04:30.840 --> 00:04:34.390
So he started to count his cherries in 100s.
00:04:35.130 --> 00:04:41.310
100, 200, 300.
00:04:42.590 --> 00:04:46.850
Mason also bought some watermelons, which come in boxes of 10.
00:04:48.110 --> 00:04:53.140
So we need to start counting at 300 and keep on counting in 10s.
00:04:54.020 --> 00:05:03.590
300, 310, 320, 330, 340.
00:05:04.600 --> 00:05:20.790
Now, we know that Mason had 340 pieces of fruit, the three numbers that he should say after 310 are 320, 330, and 340.
00:05:21.440 --> 00:05:28.100
First, Mason counted his cherries in 100s: 100, 200, 300.
00:05:28.640 --> 00:05:37.110
He counted his watermelons in 10s: 310, 320, 330, 340.
00:05:38.120 --> 00:05:44.220
So the missing numbers are 320, 330, and 340.
00:05:46.760 --> 00:05:49.280
He also bought some oranges.
00:05:50.170 --> 00:05:54.550
Count on to figure out how many pieces of fruit he has in total.
00:05:55.640 --> 00:05:58.640
We know that Mason bought three boxes of cherries.
00:05:58.780 --> 00:06:01.410
Each box contained 100 cherries.
00:06:01.910 --> 00:06:06.300
And he bought four boxes of melons, and the melons came in boxes of 10.
00:06:07.130 --> 00:06:09.960
So we can start counting at 100.
00:06:10.660 --> 00:06:15.570
100, 200, 300.
00:06:16.160 --> 00:06:21.750
We need to keep on counting in 10s now because the watermelons came in boxes of 10.
00:06:22.490 --> 00:06:30.490
310, 320, 330, 340.
00:06:31.470 --> 00:06:34.470
And we can count the oranges in ones.
00:06:35.410 --> 00:06:37.820
The oranges are single pieces of fruit.
00:06:37.990 --> 00:06:41.120
They haven’t been grouped together in 10s or 100s.
00:06:41.260 --> 00:06:42.930
We count these as ones.
00:06:43.700 --> 00:07:00.380
341, 342, 343, 344, 345, 346, 347.
00:07:01.360 --> 00:07:05.590
We counted in 100s, 10s, and ones.
00:07:06.310 --> 00:07:12.320
The total number of pieces of fruit that Mason bought is 347.
00:07:15.340 --> 00:07:16.790
Count the marbles.
00:07:17.940 --> 00:07:27.760
In this question, we’re shown some different jars of marbles, these two jars of marbles both contain 100 marbles.
00:07:28.550 --> 00:07:32.080
These three jars each contain 10 marbles.
00:07:33.230 --> 00:07:35.250
These marbles haven’t been grouped.
00:07:35.510 --> 00:07:37.700
We count these as ones.
00:07:38.660 --> 00:07:45.570
So to count the marbles, we need to count in 100s, 10s, and ones.
00:07:46.210 --> 00:07:48.510
Let’s start counting in 100s.
00:07:49.160 --> 00:07:52.300
100, 200.
00:07:53.300 --> 00:07:59.940
We counted in 100s twice because there are two jars of marbles and each jar contains 100 marbles.
00:08:00.870 --> 00:08:08.540
Next, we need to count forward in 10s because we’ve got three jars of marbles each containing 10 marbles.
00:08:09.110 --> 00:08:14.680
We’re going to start at 200 and count forward in 10s three times.
00:08:15.460 --> 00:08:22.200
210, 220, 230.
00:08:23.250 --> 00:08:26.210
Now what we need to do is count forward in ones.
00:08:26.820 --> 00:08:31.540
231, 232.
00:08:32.800 --> 00:08:37.390
We counted the marbles in 100s, 10s, and ones.
00:08:38.160 --> 00:08:41.140
There were 232 marbles.
00:08:43.610 --> 00:08:46.540
There are 100 balls in each bag.
00:08:47.460 --> 00:08:48.980
How many balls are there?
00:08:50.280 --> 00:08:53.900
We can see that there are three bags of balls.
00:08:54.990 --> 00:08:59.520
And we know that each bag contains 100 balls.
00:09:00.000 --> 00:09:05.080
So to count the number of balls in the bags, we need to count in 100s.
00:09:05.770 --> 00:09:10.960
100, 200, 300.
00:09:12.130 --> 00:09:14.980
But that isn’t the total number of balls.
00:09:15.790 --> 00:09:17.780
We have to count these ones too.
00:09:18.790 --> 00:09:24.020
They haven’t been grouped, so we can count these as ones.
00:09:25.250 --> 00:09:27.200
There are four ones.
00:09:27.990 --> 00:09:39.370
301, 302, 303, 304.
00:09:40.630 --> 00:09:43.180
First, we counted in 100s.
00:09:45.310 --> 00:09:47.450
Then, we counted in ones.
00:09:48.950 --> 00:09:53.260
We had three 100s and four ones.
00:09:53.860 --> 00:09:59.230
Did you notice that there were no 10s, only 100s and ones?
00:10:00.820 --> 00:10:04.040
The total number of balls is 304.
00:10:07.200 --> 00:10:11.790
Count in 100s and 10s to write the missing numbers.
00:10:12.190 --> 00:10:22.120
100, 200, 300, what, 410, what and what.
00:10:23.300 --> 00:10:26.230
In this question, we’re shown some place-value blocks.
00:10:27.330 --> 00:10:30.160
And we need to count those in 100s.
00:10:31.080 --> 00:10:38.500
100, 200, 300, 400.
00:10:39.320 --> 00:10:42.280
We know the first missing number is 400.
00:10:43.510 --> 00:10:54.490
Now we need to continue counting in 10s: 410, 420, 430.
00:10:55.670 --> 00:11:04.720
100, 200, 300, 400, 410, 420, 430.
00:11:05.920 --> 00:11:12.610
The missing numbers are 400, 420, and 430.
00:11:14.990 --> 00:11:16.890
What have we learned in this video?
00:11:17.990 --> 00:11:27.590
We’ve learned how to count on to find the total when objects are grouped in 100s, 10s, and ones.
00:11:28.610 --> 00:11:34.430
We’ve also learned how to model three-digit numbers using place-value equipment.