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Current time:0:00Total duration:12:11

Video transcript

in the last video we went over the multiplication tables for 1 through 9 and I ran at a time and it actually was a good thing because 1 through 9 are kind of the core multiplication tables and you'll see that if you know all your multiplication tables from 1 to 9 so you know any number between 1 and 9 times any other number between 1 and 9 you can actually do any multiplication problem out there but what I want to do now is I want to complete the multiplication tables for 10 11 and 12 so what is 10 times let's just start at 0 10 times 0 anything times 0 is 0 10 zeros are 0 0 plus 0 plus 0 10 times is still 0 what's 10 times 1 10 times 1 well that's just 10 one time or one plus itself 10 times that's 10 I think this is second nature to you at this point what's 10 times 2 10 times 2 meant to switch colors but I didn't 10 times 2 that's 10 plus 10 which is 20 fair enough and notice we went up by 10 the first time we went up by 10 again to get to 20 what's 10 times 3 well that's 10 plus 10 plus 10 or we could view it as 10 times 2 plus another 10 which is equal to 30 what's 10 times 4 I think you start to see a pattern a 10 times 4 is equal to 40 notice 10 times 4 is equal to 40 if I were to tell you what is 10 times let me do another color 5 well that's equal to 50 50 10 times anything 10 times anything is that anything with a zero behind it so the 10 times tables you almost won't have to remember it so let's just let's just keep going what's 10 times 6 it's equal to 66 zero what's 10 times 7 seventy ten times a this is almost ridiculous ten times eight is eighty ten times nine ninety ten times ten now this is interesting ten times ten so it'll be a ten let's see me write this ten times let me do it in a in this orange color ten times ten so it'll be ten tens or ten with a zero behind it there you go notice everything I'm just whatever times ten I just add a zero and I get the next number so it's a hundred and I think you understand why that is I had a ten to itself 10 times that each 10 you know you go from 10 20 30 30 is just three tens or ten times three 90 is just nine tens or nine times ten let's keep going so 10 times 11 is equal to 11 with the zero behind it 110 finally 10 times 12 10 times 12 is equal to 120 now just just for fun these are your kind of your 10 times tables but now that you know the pattern you can do anything if I asked you what 5732 times 10 is times 10 what's it going to be it's going to be this number with just one more zero so it's going to be I won't read it out get at five seven three two with the zero behind it and just so you know this little comma that I wrote it in the number there let's just make it easier for me to read that number so and you put the comma you start over here and every third number you put the comma so here I'm going to put the comma right here I'm going to put the comma right there so now I can read this because it calm the comma doesn't really add or to take anything away from the number just helps me read it now 5732 times ten is fifty seven thousand three hundred and twenty I just had to add a zero there but that was a pretty straightforward multiplication and those we had five thousand times ten and we got 250 something thousand when we multiply them so that's similar to five times 10 is equal to 50 but instead of five I had a 5000 and so I got a 50,000 in something and there's all this other stuff we're going to learn more about how to do problems like this in the future but I thought I would introduce you to the idea that just from this little pattern of adding a 0 you already know your tens times tables now let's do our 11s our 11 so 11 is get a little bit well they start off easy then they get a little a little more difficult as we get into high numbers so 11 times 0 this is easy this is 0 11 times 1 this is also easy it's 11 11 times 2 we're going to start seeing a pattern here it's 11 plus 11 or we could add 2 to itself 11 times but that is equal to 22 if we do 11 times 3 it is equal to 33 11 times 4 is equal to 44 I think this is becoming obvious to you what's 11 times 5 11 times 5 is 55 I just put the 5 twice what's 11 times 6 it's 66 11 times 7 is 84 not kidding I didn't want to mess with you like that but no of course it's 77 77 you just repeat the number twice 77 let me switch colors 11 times 8 is equal to 88 11 times 9 is equal to 99 now what's 11 times 12 11 times 12 you might I'm sorry I skipped 10 11 times 10 you might want to say it's 10 to 10 no that's wrong it's not 10 to 10 like 19 it's not 10 to 10 so that little pattern that we had where you just repeat the number that only worked for one digit number so it only works for one through nine 11 times 10 well we could think about it a couple of ways we can add 11 to 99 so we could say it's 99 plus 11 and what's that that's equal to 110 and I'm going to show you how to do well hopefully you've already watched the video on how to add two-digit numbers like this but that's 110 or you could just use the property from the tens times tables that we learned where if you just take 11 times 10 you add a zero to the 11 you get 100 and ehn right that's the 11 right there finally let's do 11 times 12 11 times 12 no easy way to remember this you just kind of should remember it or you can say look it's going to be 11 more than 11 times sorry I keep skipping things we should do 11 times 11 first let me make sure this is clear we're doing 11 times 11 before we go to 11 times 12 so 11 times 11 it's going to be 11 more then 11 times 10 right so we add 11 to this 11 plus 110 is 121 121 and actually as you'll see there actually is an order as we get to higher multiples of 11 but I'll leave that to a future video and then finally we're at 11 times 12 11 times 12 and we could add 11 to itself 12 times we could add 12 to itself 11 times or we could just say hey this is going to be 11 more 11 more then 11 times 11 so that is what you add 11 to this and what you get you get 132 132 I just added 121 plus 11 and then got 132 now the other way you could have said is what's 10 times 12 10 times 12 we already knew that that was 120 so 11 times 12 because we're multiplying 12 by one more should be 12 more than that so that should be 132 so two ways to get the exact same answer all right now let's do our 12 times tables 12 times tables and it's once you know this you are ready to tackle any type of multiplication problem we'll do that in future videos so 12 times 0 super-easy 0 12 times 1 also super easy is 12 now it gets interesting we're going to increment increase by 12 every time 12 times 2 is equal to 24 12 plus 12 is 24 right 12 times not 22 let me rewrite that 12 times 3 is going to be 12 plus 12 plus 12 or we right that is 12 times 2 why not you see my brain is doing the wrong things we could rewrite that as 12 times 2 plus 12 or we could rewrite that as 24 plus 12 either way all of these get us to 36 and that's notice that's just that plus 12 12 times 4 12 times 4 is equal to 48 and you wait there's a lot of ways you could think about you could say 11 times 4 is 44 right 11 times 4 is equal to 44 and you could say that's you go up by one more four so you get to 12 times four or you could say 12 times 3 is 36 and you can add 112 to it to get to 48 either way works and that's because we can multiply in either direction let's keep going 12 times 5 is equal to 60 all right 10 times 5 is 50 11 times 5 is 55 so 12 times 5 is 60 12 times 6 is equal to what it's going to be 12 more than this it's going to equal 72 12 times 7 12 more than this again 12 more than 72 is 84 and I'm serious you know I'm probably a lot older than you are and still because I might have I still in my head to confirm I go to some 12 times tables that I remember is definitely right like Oh 12 times 5 and sometimes in my head I say oh let me add another 12 oh yeah definitely my memory was correct correct 12 times 6 is 72 all right then you go to 12 times 8 at 12 to the 12 times 7 96 12 times 9 12 times 9 well you had 12 to this so it's 108 108 and then 12 times 10 this is an easy one right we just add a 0 to the 12 you get 120 or we could add 12 to 108 either way 12 times 11 12 times 11 we just did this add 12 to this you get to 132 and then 12 times 12 is equal to 144 this actually shows up if I had a dozen of dozen eggs a dozen is 12 or if I had eight I think a gross is actually 12 dozen so that's 144 eggs so you'll actually end up seeing this number a lot more than you would expect in life but anyway we've now completed all of our all of our multiplication tables and I really encourage you to take the time now to go and memorize them make some flashcards use its use the the little software thing that I wrote on my website you could try that out as as of September 2009 it's it's working I haven't touched it in a while but I'm going to I'm actually probably going to rebuild it soon so if you're watching this video in the Year 2200 well I would have probably not exist anymore but hopefully you'll get a better version of the software app but you should practice it you should get your parents to quiz you you should get quiz note cards you should just be mumbling to yourself as you walk to school what is 12 times 9 what is 11 times 11 and you should quiz each other because it'll pay huge rewards to you later on in life see in the next video