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00:00Today our lesson is on addition with regrouping.
00:11And we are going to do addition of 3 digit numbers.
00:22Now this is the problem we are going to do today.
00:25Let us read it, 157 add 185 and we are going to do it how we learned to do it.
00:34So we know that first we add the 1s column.
00:38So we have 7 add 5.
00:41So 7 add 5 will give us 12.
00:45What do we do next?
00:47We take the 2 and we put the 2 in the 1s column.
00:53Then we move on to the 10s column, 8 add 5.
00:58Remember we keep the bigger number in our head and then we count on.
01:01So after 8 we count 5 more, after 8, 9, 10, 11, 12, 13 and then we add the 1 from the
01:1212 and we get 14.
01:16What do we do with the 14?
01:19We take the 4 and we put it in the 10s column.
01:24Then we add our 100s, 1 add it to 1 makes 2.
01:31And then we add the 1 from outside, 2 add 1 is 3.
01:37But this can be very very confusing especially for children.
01:42So we need to know why we do what we do.
01:48And most of the times we learn this because of drills and because of repetition.
01:54So I am going to show you why we do what we do and the reasoning behind it.
02:02So we are going to do the same problem but this time we are going to use base 10 blocks.
02:07So here I have the numbers represented using the base 10 blocks.
02:11In the first row we have 100, 5 10s and 7 1s.
02:17So that is 157.
02:20In the second row we have 100, 8 10s and 5 1s.
02:28So we have 185.
02:32Now we know that 7 added to 5 will give us 12.
02:37So we have 12 1s but we cannot put the 12 1s in the 1s column.
02:43So we are going to take out 10 1s to regroup it.
02:48We know that 10 1s make up 1 10.
02:53So count with me, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
03:09What do we do with the 10 1s?
03:12We trade it for 1 10 because 10 1s make up 1 10.
03:20So we add a 10 to the 10s column and how many 1s do we have remaining?
03:25We have 2 1s remaining.
03:27So we are going to put the 2 in the 1s column.
03:36So here we see we have our 2 1s and we have our 10s and we have our 100s.
03:42Now 8 add 5 is 13 but remember we added a 10 to the 10s column because we traded the
03:5210 1s for 1 10.
03:54So now we have 14 10s but we cannot put 14 10s under the 10s.
04:00So I am going to take out 10 10s and you would know from a previous lesson that 10 10s is
04:06the same as 100.
04:09So count with me, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
04:27So we took out our 10 10s and what are we going to do with it?
04:32We are going to trade it for 100.
04:36So we are just exchanging it.
04:38We are going to trade it for 100.
04:41How many 10s do we have remaining?
04:42We have 4 10s remaining.
04:45So we are going to put the 4 10s under our 10s and then we have 3 100s.
05:00So here we have another problem and we are going to do it using the Beast 10 blocks.
05:05So we have 249 added to 174.
05:13So you see we have it represented here, 200s, 4 10s, 9 1s and then we have 100, 7 10s and
05:214 1s.
05:23So we are going to add our 1s first, 9 and 4.
05:28Remember we keep the bigger number in our head.
05:30So after 9 we have 10, 11, 12, 13.
05:36So we are going to trade our 10 1s for 1 10.
05:42Count with me, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
05:58And we take our 10 1s and we trade it for 1 10.
06:03So what do we have remaining in the 1s column?
06:06We have 3 1s remaining in the 1s column.
06:16So here we have our 3 1s and remember we added 1 10 to the 10s column.
06:23So we have 7 added to 4 will give us 11 but we have to remember the extra 1 10 which we
06:32added.
06:33So it will give us 12.
06:35So we have 12 10s.
06:37Now we cannot put 12 10s in the 10s column.
06:42So we are going to regroup our 10s.
06:45So let us take out 10 10s.
06:49Count with me, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
07:08So to count our 10 10s, we are going to trade it for 100 because 10 10s is the same as 100.
07:21How many 10s we have remaining in the 10s column?
07:24We have 2 10s.
07:27And now we will count our 100s.
07:29We have 4 100s, 1, 2, 3, 4 100s.
07:35And there we have it boys and girls using our base 10 blocks.
07:45Now that we have a better understanding of regrouping and a reasoning behind doing the
07:50different operations, we are going to do this problem without using the base 10 blocks.
07:57So we have 193 added to 389.
08:03So let us add our 1s column first.
08:06We have 3 and 9.
08:08Now I'm sure you would remember in a previous lesson we learned that you will keep the bigger
08:14number in your head and then count on.
08:17So we say after 9, 10, 11, 12.
08:21Now this 12 represents 12 1s.
08:27So you can picture the base 10 blocks.
08:30You have 12 1s.
08:33We cannot put the 12 1s in the 1s column.
08:35So we are going to regroup.
08:37We are going to take out our 10 1s and we are going to remain with only 1s.
08:44So when we take out the 10 1s, we know we will regroup the 10 1s into 1, 10.
08:50And we will remain with our 2 1s, which we will put under the 1s.
08:56Then we have 9 and 8.
08:599 and 8 will give us 17.
09:03So we have 17 10s and we have to add in the 1, 10, which will give us 18 10s.
09:13So this 18 represents 18 10s.
09:17We cannot put the 18 10s under the 10s, so we are going to regroup.
09:21We are going to take out 10 10s because we know 10 10s is the same as 100.
09:29When we take out the 10 10s, we remain with 8 10s, which we put in our 10s column.
09:36And then we add our 100s.
09:38We have 3 and 1 equals 4, 400s.
09:45And then we add the 10 10s, which we had regrouped.
09:51Remember when we traded, we traded the 10 10s for 100.
09:54So you have 3 and 1 is 4 and 1 is 5.
10:00And here we have our regrouping.
10:03So I am going to show you how you can make your base 10 blocks at home using simple materials
10:10and you can use it to complete the exercise, which you will get at the end.
10:18Here I made my own base 10 blocks.
10:20I used colored paper.
10:22If you do not have colored paper, you can take a plain sheet of paper and you color
10:26it and then you get someone to help you to cut it out.
10:30And you can use it to do the problems that we have on the next page.
10:39So I have some problems for you to complete.
10:41You are going to do it in hundreds, tens and ones.
10:45You are free to use your own base 10 blocks or you could do it without the base 10 blocks.
10:50But once you have the understanding of why you are doing what you are doing.
10:56I hope that this video helped you and you have a better understanding of the reasoning
11:03behind doing addition with regrouping.