1 00:00:00,813 --> 00:00:04,716 A farmer grows 531 tomatoes 2 00:00:04,716 --> 00:00:08,600 and is able to sell 176 of them 3 00:00:08,600 --> 00:00:10,352 in three days. 4 00:00:15,753 --> 00:00:20,467 Given that his supply of tomatoes decreases by 176, 5 00:00:20,467 --> 00:00:23,385 how many tomatoes does he have remaining 6 00:00:23,385 --> 00:00:25,194 at the end of three days? 7 00:00:25,194 --> 00:00:30,419 So he starts with 531 tomatoes 8 00:00:30,419 --> 00:00:32,578 let me give myself a little more space to work with 9 00:00:32,578 --> 00:00:36,341 -- he starts with 531 tomatoes 10 00:00:36,341 --> 00:00:38,973 and he is able to sell 176. 11 00:00:38,973 --> 00:00:41,215 He is essentially going to subtract 12 00:00:41,215 --> 00:00:43,508 the 176 that he is selling. 13 00:00:43,508 --> 00:00:44,856 If we want to figure out 14 00:00:44,856 --> 00:00:46,370 how many he is left with, 15 00:00:47,685 --> 00:00:49,000 we are going to subtract 176. 16 00:00:49,000 --> 00:00:50,458 That‘s how many he sells in three days. 17 00:00:50,458 --> 00:00:51,801 They're asking us: 18 00:00:51,801 --> 00:00:53,867 how many does he have left at the end of three days? 19 00:00:53,867 --> 00:00:56,169 We just have to subtract those 176 20 00:00:56,169 --> 00:00:57,887 from the amount he grew. 21 00:00:57,887 --> 00:01:00,906 It turned into this straight up subtraction problem. 22 00:01:00,906 --> 00:01:02,717 Lets see if we can do it. 23 00:01:02,717 --> 00:01:05,550 If we go straight to the ones place 24 00:01:05,550 --> 00:01:06,711 right over here 25 00:01:06,711 --> 00:01:08,333 and actually let me do it in parallel 26 00:01:08,333 --> 00:01:10,193 because i think that might be interesting over here. 27 00:01:10,193 --> 00:01:11,415 I'm going to do it the way 28 00:01:11,415 --> 00:01:13,295 you traditionally do it here on the left 29 00:01:13,295 --> 00:01:14,548 and then I'm going to show you 30 00:01:14,548 --> 00:01:16,133 what's happening here on the right. 31 00:01:16,133 --> 00:01:18,154 So 531 is the same thing 32 00:01:18,154 --> 00:01:21,247 as 500 + 30 + 1 33 00:01:21,247 --> 00:01:24,000 and if you subtract 176 34 00:01:24,000 --> 00:01:25,440 that is the same thing as subtracting 100 35 00:01:25,440 --> 00:01:29,625 and subtracting another 70 and subtracting another 6 36 00:01:29,625 --> 00:01:31,264 I wrote it this way 37 00:01:31,264 --> 00:01:34,250 because the 5 in 531 is the same thing as 500 38 00:01:34,250 --> 00:01:37,361 The 3 in 531 is in the tens place 39 00:01:37,361 --> 00:01:39,062 so it's really representing 30 40 00:01:39,062 --> 00:01:42,200 the 1 in 531 is in the ones place 41 00:01:42,200 --> 00:01:43,800 so it represents one 42 00:01:43,831 --> 00:01:44,744 and now 43 00:01:44,744 --> 00:01:45,863 it'll be a little bit clearer 44 00:01:45,863 --> 00:01:47,008 what we're doing 45 00:01:47,008 --> 00:01:48,348 when we're borrowing or regouping 46 00:01:48,348 --> 00:01:51,236 on this problem right over here 47 00:01:51,236 --> 00:01:53,413 and so let's start off with the ones place 48 00:01:53,444 --> 00:01:56,578 one is less than 6 49 00:01:56,578 --> 00:01:59,838 be great if we can regoup some of the values 50 00:01:59,838 --> 00:02:01,125 from the rest of the places 51 00:02:01,125 --> 00:02:03,228 so we can go to staright to the tens place 52 00:02:03,228 --> 00:02:05,375 the tens place we can borrow 53 00:02:05,375 --> 00:02:06,805 or regroup ten from it 54 00:02:06,805 --> 00:02:07,687 so if we take ten from here 55 00:02:07,687 --> 00:02:09,219 this becomes 20 56 00:02:09,219 --> 00:02:11,882 we're going to take that 10 and add it to the 1 57 00:02:11,944 --> 00:02:14,667 so this will become 11 58 00:02:14,667 --> 00:02:16,278 we just added a 10 59 00:02:16,302 --> 00:02:19,343 we moved over 10 from the tens place 60 00:02:19,343 --> 00:02:20,550 to the ones place 61 00:02:20,550 --> 00:02:22,036 if you look at it over here 62 00:02:22,036 --> 00:02:25,134 you could say: Look! we're taking 10 from the 30 63 00:02:25,134 --> 00:02:26,538 that becomes a 20 64 00:02:26,538 --> 00:02:29,420 and then the 1 becomes an 11 65 00:02:29,420 --> 00:02:31,417 the way when i was first in school 66 00:02:31,417 --> 00:02:32,485 people say you borrow one 67 00:02:32,485 --> 00:02:33,739 from the three 68 00:02:33,739 --> 00:02:36,000 and you kind of just stick the one right over here 69 00:02:36,000 --> 00:02:37,176 but what you're really doing 70 00:02:37,176 --> 00:02:38,755 is you're taking a 10 from a 30 71 00:02:38,755 --> 00:02:40,638 and making it into a twenty 72 00:02:40,638 --> 00:02:43,359 and you're getting a- you're adding the ten to the one 73 00:02:43,359 --> 00:02:44,075 getting 11 74 00:02:44,075 --> 00:02:46,046 but either way you'll end up with 11 75 00:02:46,046 --> 00:02:47,021 in the ones place 76 00:02:47,021 --> 00:02:48,414 and now you can subtract 77 00:02:48,414 --> 00:02:52,920 11 - 6 is 5 78 00:02:52,920 --> 00:02:54,867 now we go over to the tens place 79 00:02:54,867 --> 00:02:56,959 in the tens place 80 00:02:56,959 --> 00:02:59,235 we now have 2-7 81 00:02:59,235 --> 00:03:03,680 which is really representing 20-70 82 00:03:03,680 --> 00:03:06,728 well we - thats 70 is bigger than the 20 83 00:03:06,728 --> 00:03:08,333 so we want to add some more 84 00:03:08,333 --> 00:03:09,127 to the tens place 85 00:03:09,127 --> 00:03:10,933 well we can go the hundreds place 86 00:03:10,933 --> 00:03:12,871 to find some more value to regroup 87 00:03:12,871 --> 00:03:14,809 so let's see if we can do that 88 00:03:14,809 --> 00:03:16,052 we have 500 here 89 00:03:16,052 --> 00:03:18,637 so what happens when we take a hundred from that 90 00:03:18,637 --> 00:03:20,458 so we're just left with 400 from here 91 00:03:20,458 --> 00:03:22,733 and we take that 100 and we put it in 92 00:03:22,733 --> 00:03:24,359 the tens place 93 00:03:24,359 --> 00:03:29,121 so instead of 20 we now have 120 94 00:03:29,182 --> 00:03:31,067 if you look at it on this problem 95 00:03:31,067 --> 00:03:32,805 since we are using the places here 96 00:03:32,805 --> 00:03:36,805 we're going to take 100 from the 500 97 00:03:36,805 --> 00:03:37,873 and have 400 98 00:03:37,873 --> 00:03:40,289 and then we're going to take that 100 99 00:03:40,289 --> 00:03:42,000 that we took and take it to the tens place 100 00:03:42,000 --> 00:03:43,267 well 100 is 10 tens 101 00:03:43,267 --> 00:03:45,333 so we're going to add 10 to this 102 00:03:45,333 --> 00:03:47,067 so this is going to become a 12 103 00:03:47,067 --> 00:03:48,693 once again, the way- 104 00:03:48,693 --> 00:03:51,400 the kind of more mechanical rope way of thinking about it is that 105 00:03:51,400 --> 00:03:53,324 -oh- you took one away from the four 106 00:03:53,324 --> 00:03:56,733 and you stick that one in front on the two 107 00:03:56,733 --> 00:04:01,729 but you're really taking a 100 from the 500, making it 400 108 00:04:01,729 --> 00:04:04,344 and then adding that 100 to the 20 here 109 00:04:04,344 --> 00:04:06,248 and making it 120 110 00:04:06,248 --> 00:04:07,873 but your writing here is a 12 111 00:04:07,873 --> 00:04:09,034 because it is 12 tens 112 00:04:09,034 --> 00:04:10,567 you're at the tens place 113 00:04:10,567 --> 00:04:11,635 so let me write it down 114 00:04:11,635 --> 00:04:12,563 this is the ones place 115 00:04:12,563 --> 00:04:14,375 this is tens place 116 00:04:14,375 --> 00:04:19,462 and this is the hundreds place 117 00:04:19,462 --> 00:04:23,941 so now that our numbers on top in the tens place 118 00:04:23,941 --> 00:04:25,952 is bigger than the numbers on the bottom 119 00:04:25,952 --> 00:04:27,039 we can subtract 120 00:04:27,039 --> 00:04:31,047 so we get 120-70 that is 50 121 00:04:31,047 --> 00:04:33,503 or 12 minus 7 is 5 122 00:04:33,508 --> 00:04:35,180 5 is in the tens place 123 00:04:35,180 --> 00:04:36,944 so it's really representing 50 124 00:04:36,944 --> 00:04:38,867 let me circle it with the same colour 125 00:04:38,867 --> 00:04:40,856 so you recognise that 126 00:04:40,856 --> 00:04:43,205 this 5 is representing 50 127 00:04:43,205 --> 00:04:47,151 then finally we're in the hundreds place 128 00:04:47,161 --> 00:04:50,400 so 400 -100 is 300 129 00:04:50,446 --> 00:04:52,270 4-1 is 3 130 00:04:52,270 --> 00:04:54,000 but this 3 represents 300 131 00:04:54,000 --> 00:04:55,133 this 5 represents 50 132 00:04:55,133 --> 00:04:57,099 this 5 represents 5 133 00:04:57,099 --> 00:04:58,260 so we're done 134 00:04:58,260 --> 00:04:59,839 we get 355 135 00:04:59,839 --> 00:05:03,133 the farmer is left with 355 tomatoes 136 00:05:03,133 --> 00:05:04,576 at the end of 3 days 137 00:05:04,576 --> 00:05:08,671 or 300+50+5 tomatoes.