1 00:00:00,808 --> 00:00:05,740 Let's think about what it means to add numbers. 2 00:00:05,740 --> 00:00:14,674 So let's start with one. One plus -- one plus one. 3 00:00:14,674 --> 00:00:18,301 What is this going to be equal to? 4 00:00:19,207 --> 00:00:24,097 One way to think about this is we have one thing. 5 00:00:24,097 --> 00:00:28,953 And I will -- that thing will be a purple circle. 6 00:00:28,953 --> 00:00:31,497 So let me put that here. 7 00:00:31,497 --> 00:00:33,427 So that's this 1 thing. 8 00:00:33,427 --> 00:00:35,512 I'm just going to represent it with a purple circle. 9 00:00:35,529 --> 00:00:37,479 And I'm going to add another 1 thing. 10 00:00:37,479 --> 00:00:40,069 And since this is in blue, I'll make that other circle. 11 00:00:40,069 --> 00:00:41,835 I'll make that in blue as well. 12 00:00:42,277 --> 00:00:44,802 So, let me put that right over here. 13 00:00:45,314 --> 00:00:48,185 So, 1 plus 1. 1 plus 1. 14 00:00:48,384 --> 00:00:51,642 How many total circles do I now have? 15 00:00:51,848 --> 00:00:54,529 Well, I now have 2 circles. 16 00:00:55,030 --> 00:00:57,666 I now have 2 circles. 17 00:00:57,994 --> 00:01:04,226 1 plus 1 is equal to 2. 18 00:01:04,649 --> 00:01:07,910 OK, you're saying, "All right, Sal, that makes sense." 19 00:01:07,920 --> 00:01:11,167 Let's do this with larger numbers. 20 00:01:11,419 --> 00:01:14,941 So let's say we want to know what equals-- 21 00:01:14,948 --> 00:01:18,673 and I'll put a question mark over here. So, question mark. 22 00:01:19,013 --> 00:01:20,783 What equals -- 23 00:01:20,793 --> 00:01:34,029 So something is equal to, let's say, 2, 2, 2 plus 3. 24 00:01:34,029 --> 00:01:38,077 Something is equal to 2 plus 3. 25 00:01:38,077 --> 00:01:41,431 What is this something going to be? 26 00:01:41,751 --> 00:01:45,530 And I encourage you to pause the video and think about it on your own. 27 00:01:46,234 --> 00:01:48,879 Well, you can view this as, I have 2 objects, 28 00:01:48,879 --> 00:01:51,131 and then I am going to add another 3 objects. 29 00:01:51,131 --> 00:01:54,116 How many total objects would I have? 30 00:01:54,116 --> 00:02:01,062 So you have your 2 objects, which I'll use purple circles again. 31 00:02:01,071 --> 00:02:02,430 So let me -- 32 00:02:02,988 --> 00:02:09,396 Let me, so we have 1 and 2 purple circles. 33 00:02:09,396 --> 00:02:11,066 This is the 2 right over here. 34 00:02:11,066 --> 00:02:14,074 And then to that, we're going to add 3 more. 35 00:02:14,083 --> 00:02:15,665 3 more circles. 36 00:02:15,665 --> 00:02:19,766 And I'll represent those in blue, because we wrote the 3 there in blue. 37 00:02:20,155 --> 00:02:28,366 So that is 1, 2, and 3. 38 00:02:29,542 --> 00:02:33,212 So how many total circles do we now have? 39 00:02:33,714 --> 00:02:38,599 Well, we can count them. We have 1,2,3,4,5. 40 00:02:38,599 --> 00:02:45,023 In fact, let me count that. 1,2,3,4,5 circles. 41 00:02:45,282 --> 00:02:46,806 So 2 plus 3 42 00:02:46,806 --> 00:02:50,799 2 things plus another 3 things are 5 things. 43 00:02:50,799 --> 00:02:54,799 So our question mark over here is equal to 5. 44 00:02:55,049 --> 00:02:56,821 So, instead of writing the question mark 45 00:02:56,821 --> 00:02:59,699 right over here, let me clear that out. 46 00:02:59,699 --> 00:03:02,236 I could say 5 is equal to -- 47 00:03:02,733 --> 00:03:09,728 I could write down that 5 is equal to 2 plus 3.