WEBVTT 00:00:00.715 --> 00:00:06.990 We need to calculate 9.005 minus 3.6, or we could view it 00:00:06.990 --> 00:00:13.067 as 9 and 5 thousandths minus 3 and 6 tenths. 00:00:13.067 --> 00:00:15.800 Whenever you do a subtracting decimals problem, the most 00:00:15.800 --> 00:00:18.063 important thing, and this is true when you're adding decimals as well, 00:00:18.078 --> 00:00:20.573 is you have to line up the decimals. 00:00:20.573 --> 00:00:31.877 So this is 9.005 minus 3.6. 00:00:31.877 --> 00:00:34.863 So we've lined up the decimals, and now we're ready 00:00:34.863 --> 00:00:36.867 to subtract. 00:00:36.867 --> 00:00:38.667 Now we can subtract. 00:00:38.667 --> 00:00:40.133 So we start up here. 00:00:40.133 --> 00:00:41.533 We have 5 minus nothing. 00:00:41.533 --> 00:00:44.582 You can imagine this 3.6, or this 3 and 6 tenths. We could 00:00:44.582 --> 00:00:47.867 add two zeroes right here, and it would be the same thing as 00:00:47.867 --> 00:00:52.600 3 and 600 thousandths, which is the same thing as 6 tenths. 00:00:52.600 --> 00:00:54.335 And when you look at it that way, you'd say, OK, 5 minus 0 00:00:54.335 --> 00:00:57.267 is nothing, and you just write a 5 right there. 00:00:57.267 --> 00:00:59.000 Or you could have said, if there's nothing there, it 00:00:59.000 --> 00:01:00.743 would have been 5 minus nothing is 5. 00:01:00.743 --> 00:01:04.467 Then you have 0 minus 0, which is just 0. 00:01:04.467 --> 00:01:07.600 And then you have a 0 minus 6. 00:01:07.600 --> 00:01:10.200 And you can't subtract 6 from 0. 00:01:10.200 --> 00:01:12.818 So we need to get something into this space right here, 00:01:12.818 --> 00:01:14.933 and what we essentially are going to do is regroup. 00:01:14.933 --> 00:01:21.084 We're going to take one 1 from the 9, so let's do that. 00:01:21.084 --> 00:01:25.124 So let's take one 1 from the 9, so it becomes an 8. 00:01:25.124 --> 00:01:26.667 And we need to do something with that one 1. 00:01:26.667 --> 00:01:28.933 We're going to put it in the tenths place. 00:01:28.933 --> 00:01:32.667 Now remember, one whole is equal to 10 tenths. 00:01:32.667 --> 00:01:34.333 This is the tenths place. 00:01:34.333 --> 00:01:37.267 So then this will become 10. 00:01:37.267 --> 00:01:39.242 Sometimes it's taught that you're borrowing the 1, but 00:01:39.242 --> 00:01:41.200 you're really taking it, and you're actually taking 10 from 00:01:41.200 --> 00:01:43.800 the place to your left. 00:01:43.800 --> 00:01:46.812 So one whole is 10 tenths, we're in the tenths place. 00:01:46.812 --> 00:01:49.738 So you have 10 minus 6. 00:01:49.738 --> 00:01:50.800 Let me switch colors. 00:01:50.800 --> 00:01:52.803 10 minus 6 is 4. 00:01:52.803 --> 00:01:55.821 You have your decimal right there, and then you have 8 00:01:55.821 --> 00:01:58.533 minus 3 is 5. 00:01:58.533 --> 00:02:02.533 So 9.005 minus 3.6 is 5.405.