WEBVTT 00:00:00.000 --> 00:00:00.520 00:00:00.520 --> 00:00:02.840 Janelle is training for a road race. 00:00:02.840 --> 00:00:06.090 Her pedometer tracks how far she runs every day. 00:00:06.090 --> 00:00:08.350 Here are the pedometer readings for the past four 00:00:08.350 --> 00:00:13.190 days: on Saturday, she went 3.89 miles; Sunday, 5.1; 00:00:13.190 --> 00:00:18.190 Monday, 10.21; Tuesday, 3.35. 00:00:18.190 --> 00:00:21.750 Estimate the total distance she ran over the four days, 00:00:21.750 --> 00:00:23.640 and then calculate the exact amount. 00:00:23.640 --> 00:00:26.460 Let's estimate first. So I'm just going to round them to 00:00:26.460 --> 00:00:27.380 the nearest mile. 00:00:27.380 --> 00:00:30.190 So 3.89, let's round it up to 4 miles. 00:00:30.190 --> 00:00:32.600 And I'm doing that because in the tenths place, we have an 00:00:32.600 --> 00:00:34.730 8, which is 5 or greater. 00:00:34.730 --> 00:00:38.370 So let's just make that roughly 4 miles. 00:00:38.370 --> 00:00:39.770 Let's make this 5.1. 00:00:39.770 --> 00:00:43.040 We round that down because this 1 is less than 5. 00:00:43.040 --> 00:00:45.350 So let's make this 5 miles. 00:00:45.350 --> 00:00:50.960 10.21, let's make that 10 miles because 00:00:50.960 --> 00:00:51.950 2 would round down. 00:00:51.950 --> 00:00:53.480 It's less than 5. 00:00:53.480 --> 00:00:57.470 And 3.35, let's make that 3 miles, because 3 is less than 00:00:57.470 --> 00:00:58.740 5, so we'd round down. 00:00:58.740 --> 00:01:00.610 So that is 3 miles. 00:01:00.610 --> 00:01:04.090 And if we were to add them up, 4 plus 5 is 9. 00:01:04.090 --> 00:01:07.110 9 plus 10 is 19. 00:01:07.110 --> 00:01:11.040 19 plus 3 is 22. 00:01:11.040 --> 00:01:20.040 So my estimate is that she ran 22 miles over the four days. 00:01:20.040 --> 00:01:21.080 That's my estimate. 00:01:21.080 --> 00:01:24.200 Now let's figure out the exact amount that she ran. 00:01:24.200 --> 00:01:25.670 Let me scroll down a little bit. 00:01:25.670 --> 00:01:32.940 So we're going to have to add 3.89 to 5.1-- and remember, 00:01:32.940 --> 00:01:34.870 when you're adding decimals, you want to line up the 00:01:34.870 --> 00:01:44.390 decimal-- 10.21 and then finally 3.35. 00:01:44.390 --> 00:01:47.900 And let's add all of these up. 00:01:47.900 --> 00:01:52.500 Now we'll start in the hundredths place. 00:01:52.500 --> 00:01:56.820 There's nothing here, so 9 plus nothing plus 1 is 10, 00:01:56.820 --> 00:01:59.340 plus 5 is 15. 00:01:59.340 --> 00:02:04.910 So let's write the 5, and then carry, or regroup, the 1. 00:02:04.910 --> 00:02:06.360 Let me do this in another color. 00:02:06.360 --> 00:02:10.030 1 plus 8 is 9. 00:02:10.030 --> 00:02:12.090 9 plus 1 is 10. 00:02:12.090 --> 00:02:14.190 10 plus 2 is 12. 00:02:14.190 --> 00:02:17.240 12 plus 3 is 15. 00:02:17.240 --> 00:02:18.750 Put the 5 down. 00:02:18.750 --> 00:02:21.045 Carry, or regroup, the 1. 00:02:21.045 --> 00:02:22.810 1 plus 3 is 4. 00:02:22.810 --> 00:02:25.140 4 plus 5 is 9. 00:02:25.140 --> 00:02:26.790 9 plus 0 is still 9. 00:02:26.790 --> 00:02:33.480 9 plus 3 is 12. 00:02:33.480 --> 00:02:33.960 Write the 2. 00:02:33.960 --> 00:02:35.800 Regroup this 1 right here. 00:02:35.800 --> 00:02:38.530 I'll do it out here just so it's not part of any of these 00:02:38.530 --> 00:02:42.340 numbers, and then 1 plus 1 is 2. 00:02:42.340 --> 00:02:43.770 And then we have to remember the decimal 00:02:43.770 --> 00:02:46.010 sitting right over there. 00:02:46.010 --> 00:02:52.760 So the exact distance she ran was 22.55 miles. 00:02:52.760 --> 00:02:54.160 So our estimate wasn't too bad. 00:02:54.160 --> 00:02:55.630 It was 22 miles. 00:02:55.630 --> 00:02:58.760 We got reasonably close, within about little over a 00:02:58.760 --> 00:03:00.310 half a mile. 00:03:00.310 --> 00:03:00.799