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Current time:0:00Total duration:6:57

CCSS.Math:

let's get some practice adding numbers that involve hundreds so pause this video and see if you can add these two numbers see what you get alright now let's work through this together now there's many different ways to add decimals and you'll learn more systematic faster ways of doing it in the future but I'll show you the few ways that my brain might think about it so one way to think about it is you could say that this is 53 hundredths you could read this as either five tens and three hundredths or 53 hundredths so you could say this is 53 hundredths under its and to that you're going to add 4242 hundredths and so if I have 53 of something and I'm going to add 42 of that same something to it what am I going to get well what's 53 plus 42 well in my head I say well 50 plus 40 is ninety and three plus two is five so it's going to be 9595 hundredths and if I wanted to write that as a pure number I would write that as zero point nine five which I could read as ninety-five hundreds hundreds or nine ten and five hundredths now the other way we could have thought about is we could have broken these numbers up we could have said that this first number is five tenths plus three hundredths hundreds and then the second number we could have rewritten as four tenths plus two hundredths we make sure my decimals plus two hundredths and then we could have separately added the tenth and the hundreds so you have five tenths plus four tenth so five tenths plus four tenths and then you could separately add three hundredths plus two hundredths so three hundredths and a little trouble saying that plus two hundreds and so what do I get well five tens and four tenths we've done this in previous videos they have five of something and I had four of it that's going to be 9/10 so it's going to be 9/10 and then the three hundreds plus two hundred well that's going to be five hundredths so plus 0.05 and then 9/10 plus five hundredths is going to be and I'm saying hundredths kind of strange is going to be nine tenths and five hundredths which you could also say as 95 hundredths let's do another example one that's a little bit more involved so let's say I want to add 68 hundredths 233 hundredths what is this going to be and like always pause the video and see if you can figure it out on your own well there's a couple of ways to think about it one way we could split up the 10th and the hundreds actually let's do it that way so if we could rewrite this first number as six tenths plus eight hundredths and the second number we could write as three tenths plus three hundredths let me do that in that orange color so three tenths plus three plus 3 tenths plus three hundreds and so if I add the so if I add the six tenths and the three tenths so let me just do that I'm going to write every step here if you're doing this in your head if you're doing this on paper you would necessarily write every step here so those are the tents and then separately I'm going to add the hundredths so plus eight hundredths plus three hundredths plus three hundreds so six tenths plus 3 tenths we've done this in previous videos that's hopefully pretty straightforward by this point if it's not I encourage you to review some of those earlier videos so that's going to be nine tenths about six of something and I add give them in this case we're talking about tens I'm going to get nine of them so 9/10 and so what's this going to be well you could view this as eight hundred eight hundred plus 300 so I have eight of something and I add three of something that's going to get eleven of that something 1100 so how do we write 1100 as a decimal well one way to write it you could just view this as 0.1 one this is 1100 many people would read this as 1100 or you could view this as equaling ten hundredths ten hundredths plus one hundred hundred and ten hundredths right over here is one tenth so you could view this as one tenth and 100 so one tenth and 100 and when you add everything together what you get well you get nine tenths plus 1/10 plus 100 well now this is going to get interesting still so let's see let me rewrite this so it's going to be nine tenths and this one let me write it plus 1/10 plus that one hundredth leftover so plus that one hundred so what is this going to be so 9/10 9/10 and one tenth that's going to be nine tenths and one tenth is going to be ten ten ten tenths which is the same thing as one whole so this is just going to be equal to one so it's going to be one plus one hundredth so it's going to be one and 100 and we are done as I keep mentioning in future videos we're going to learn maybe faster ways of doing this maybe way that you might be able to do a little bit more automatically but it's really important to think about what we just went here and how we were able to think okay 1100 is the same thing as 1/10 and one hundredths and then taking that tenth and then adding it to the nine tenths that we are and said hey that's a hole and in the future we're going to be doing things like carrying with decimals but this is essentially what is happening underneath conceptually it's really important did you get a sense of that before you learn the faster methods