If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains ***.kastatic.org** and ***.kasandbox.org** are unblocked.

Main content

Current time:0:00Total duration:7:30

CCSS.Math:

what I want to introduce you to in this video is a way to classify numbers as either being even or being odd so what does it mean to be even well an even number is one where if you had that many Donuts you could split it evenly between two people so even numbers are numbers that are multiples of two so if you have two Donuts you could split them if you had two people you could give one doughnut to each person for doughnuts you could split that evenly with two people you could they could each get two doughnuts and then we can keep going all of the multiples of two these are even numbers eight ten twelve and of course we could keep going on and on and on and on and an easy way to spot an even number is that it's ones place is going to be even so for example the number thirty-two is an even number because in the ones place you have a to the number five million nine hundred 77354 well that's an even number because the ones place is even now there's one number that's an interesting one why some people sometimes say well is this one really even and that's the number zero and the number zero is even because it is a multiple of two how is it a multiple of two well 0 times two is equal to zero so zero is a multiple of two and so zero for sure is an even number and then that actually makes our looking at the ones place idea hold up because a number like a number like 150 is an even number and we can look at the ones place up and say oh we have a zero there and a zero is an even number so if in the ones place you have an even number you are looking the whole thing is going to be an even number so what are odd numbers well one way to think about them is they're the numbers that aren't even so not multiples of two not multiples not multiples of two so some examples of odd numbers well one three five seven nine and of course you can go on and on and on and just like we could look at the ones place to spot an even number you can also look at the ones place to spot an odd number the number 59 well I haven't nine over here in the ones place nine is odd so this is going to be an odd number the number 1441 has a one in the ones place that is an odd number so this whole thing is going to be odd and so what's another way why is it called odd well it'd be hard to split one thousand one thousand four hundred forty-one doughnuts you can't split it evenly between two people without breaking up a doughnut if you wanted to leave the doughnuts hole one person would have to get a large one extra doughnut than the other person you can't split it evenly the easiest way I think about odd it's not a multiple of two it's not even so another way it is not it is not even so now that we know what an odd or an even number is let's think about what happens when we operate on odd or even numbers so let's think in particular actually let me move over to the side right over here let me move over right over here let's think whoops fell off the screen let's think about what happens if I take an even number an even number plus another even number is this number the sum is it going to be even or odd well you could take some examples if I say two plus six that is going to be equal to eight well eight is an even number if I say fourteen plus four well that equals 18 once again eight in the ones place this is an even number if I say a 150 150 six plus plus 100 100 and I'm going to do a simpler number plus plus four that is equal to 160 zero in the ones place this also is an even number so it looks like all the examples that I've done so far when I add an even to an even I get an even number and I encourage you to keep trying this out I encourage you to keep trying try pick some even number than another even number add them together and you'll see that you'll keep getting even numbers and it makes sense because if you had one number that's a multiple of two and you add it to another number that's a multiple 202 it makes sense that the sum is going to be a multiple of two now what happens if you add an odd and an odd what happens if you add an odd number plus another odd number well let's try what is one plus three well that's equal to four you actually get an even number you had two odd numbers you get an even number well maybe that was just that special case but if I add 15 plus seven these are both odd numbers when I add them together I get 22 I get another even number this is interesting if I take let me say 19 plus 3 actually that gets us to 22 again we have an even number this is this is interesting what about what about let's see 23 plus 5 well that gets us to 28 once again get an even number so the pattern that seems to be forming here is that if I had it an even plus and even I get an even but also if I have an odd plus an odd then I also get an even number and then once again I encourage you to try out as many numbers as you can to see if this pattern holds and you will see that it is true and odd plus an odd number is an even now let's think about one last combination what about and even what about an even plus an odd and even plus an odd so let's say I have 2 plus 1 2 plus 1 well what is that going to be well that's going to be equal to 3 that's going to be an odd number well what about what about 4 plus 3 our plus three well that's equal to seven that's equal to an odd number and so it looks like if I have an even plus and odd and I've only tried out two cases here but I encourage you to try out many many many more to make sure that you feel good about this but an even and an odd is always going to give you an odd so this is always going to give you an odd so let's just remind ourselves even numbers there are multiples of two including zero odd numbers are just numbers that aren't multiples of two that aren't even and an even plus and even is going to be equal to an even and odd plus an odd is also going to be equal to an even we saw that we saw that multiple times but an even plus an odd that is odd