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Main content
Current time:0:00Total duration:2:50

Video transcript

what I want to show you now is a way to add numbers or a way that I sometimes add numbers when I'm doing it in my head so let's say I want to add 5 to 68 and we've already seen other ways of doing it so what I'm showing you this video is the only way to do it but it might be helpful when you're doing it in your head well when I look at a number like 68 I think well gee if I if I added just two to that I would get 270 so why don't I break up 5 into 3 and to add the 2 to 68 and then I have to add the 3 so what's that going to get me well if I break up the 5 into 3 plus 2 and the whole reason why I broke it up into 3 & 2 is so I have this 2 here to add to 68 so 5 is 3 plus 2 and to that I'm going to add 68 68 and once again the reason why I put took this 2 out is because I said hey what do I have to add to 68 to get to 70 so now I could just rewrite this as 3 plus 2 plus 68 68 but now I can add the 2 to the 68 so 2 plus 68 is going to be 2 plus 68 is 70 70 and I still have this 3 here so I have 3 plus 70 which is equal to 73 73 now it might seem like this really long way of doing it but this is just a way to think about it in your head you would say okay 5 plus 68 let's see if I add 2 to 68 I'll get to 70 and so let's see 5 is 3 plus 2 I had the two to 68 I get 270 and I have 3 left over so it's going to be 73 another way you could think about it is on a number line so let's draw ourselves a number line here let's draw a number line and let me draw some let me draw some tick marks here and let's say that this right over here this right over here is 68 and so this is going to be 70 this is going to be 70 and we're going to add 5 we're going to add 5 so if you add 5 so let me add 2 first so if I add 2 first I get to 70 so plus 2 that's what I did right over here to get to 70 and then if I if I want to add 5 of that did I have to add 3 more then I have to add 3 more and so it's going to be 70 plus 3 which of course is 73 hopefully you found that interesting