Sal uses groups of objects to determine if there is an even or odd amount. Created by Sal Khan.
- [Instructor] In this video, we're gonna learn a little bit about even numbers and odd numbers. Even numbers are numbers that can be split into two equal groups. And odd numbers are numbers that cannot be split into two equal groups. So with that understanding of even numbers and odd numbers, let's look at these animals and think about whether we have an even number of each of those animals or an odd number. So let's start with these turtles. Do we have an even number of turtles or an odd number of turtles? Pause this video and try to figure that out. All right, so let's see if we can split this number of turtles into two equal groups. Well, it looks like if I were to just split it like that, I would have two groups of four. So it looks like eight, which is the number of turtles that I have right over here. It looks like eight is an even number. Why? Because I can split it into two groups of four. Now, what about the penguins right over here? I have two penguins. Is two an even number or an odd number? Well, just like we said just now, in order for it to be an even number, I have to be able to split it into two equal groups. And I can do that just like that. I could have two equal groups of one each. So two is also, an even number. All right, let's go to these beavers right over here. I have five beavers. One, two, three, four, five. Is five an even number or an odd number? Pause the video and try to think about it. All right, let's see if we can split these five beavers into two equal groups. So let's see, maybe if I were to split them there. Well, now, I have two beavers here and three beavers over there. So those aren't equal groups. So maybe I split the beavers over here. But now, I have three in the first group and two in the second group. So I really can't split this into two equal groups. So I would say, that five is an odd number. You can't split those five beavers into two equal groups. Now, what about these seals right over here? Do we have an even number of seals or an odd number of seals? Pause this video and think about that. Okay, so we have one, two , three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15 seals that we are dealing with. So we're really thinking about is 15 an even number or an odd number? Well, let's try to split it into equal groups. So if I tried to split it like that, that is clearly not equal. We have a lot more seals here in the bottom than I have here in the top. I have six in the top and nine in the bottom. But maybe I could do something like this. Maybe I could group them like this. Now I have seven on top and I have eight on the bottom. Still not equal groups. What if I did it like this? Now, I have eight on top and seven on the bottom. So no matter how hard you try, you can't, assuming you're not cutting up a seal, you're not going to have equal groups here. You can't split into two equal groups. So 15 is an odd number. All right, now, what about these monkeys here? How many monkeys do we have? One, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13. Is 13 an even or an odd number? Pause this video and think about it. Well, let's try to divide these 13 monkeys into two equal groups. I might try to do something like this. And If I do that, I have six monkeys in the top group and seven monkeys in the bottom group. So that's not equal. But maybe if I did it like this. Well now, I have seven monkeys in this top group and six monkeys in this bottom group. So I can't divide it into two equal groups. So that tells me, because I cannot divide it into two equal groups that 13 is an odd number. And we are done.