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Rounding whole numbers to nearest hundred

CCSS.Math:

Video transcript

around twenty four thousand two hundred and fifty nine to the nearest hundred to the nearest hundred you're going to find that doing these problems are pretty straightforward but what I want to do is just think about what it means to round to the nearest hundred so I'm going to do is I'm going to draw a number line let me draw a number line here and I'm just going to mark off the hundreds on the number line so maybe we have maybe we have let's say we have 24,000 let's say this is 24,000 100 and then we go to 24,000 200 then we go to 24,000 300 and we go to twenty four thousand four hundred I think you see what I mean when I'm only marking off the hundreds I'm going up by increments of a hundred now on this number line where is twenty four thousand two hundred and fifty nine so if we look at the number line it's more than twenty four thousand two hundred and it's less than twenty four thousand three hundred and it's two hundred and fifty nine so fifty nine if this distance right here is a hundred fifty nine is right about there is right about there so that is where our number is that is twenty four thousand two hundred and fifty nine so when someone asks you to round to the nearest hundred they're literally saying round to one of these increments of a hundred that or round to whichever increment of one hundred then it is closest to and if you look at it right like this if you just eyeball it you'll actually see that it is closer to twenty four thousand three hundred then it is to twenty four thousand two hundred so when you round it you round to twenty four thousand three hundred so if you round to the nearest hundred you litter the answer literally is twenty four thousand three hundred now that's kind of the conceptual understanding of why it's even called the nearest hundred the nearest hundred is twenty four thousand three hundred but every time you do a problem like this you don't have to draw a number line and go through this whole process although you might want to think about it an easier process or maybe a more mechanical process is you literally look at the number so let me write it down again twenty four thousand two 159 we want to round to the nearest hundred so you look at the hundreds place this is the hundreds place right here and when we round that means we don't want any digits we only want zeros after the hundreds place so what you do is you look at the place one less than the place you're rounding to this is the hundreds place so you look at the five right there and if this number is five or greater if it's five six seven eight or nine you round up so five or greater you round up you round up and so rounding up in this situation it is five it is five or greater so rounding up means that we go to 24,000 I'll write the 24,000 and one since we're rounding up we make the two into a three we increment it by one so rounding up so it's twenty four thousand three hundred twenty four thousand three hundred that's what we mean by rounding up and just as a kind of a counter example if I had twenty four thousand two hundred and forty nine twenty four thousand two hundred and forty nine and I wanted to round to the nearest hundred I would say okay I want to round to the nearest hundred let me look at the tens place let's place one level to the right it is not five or greater so I will round down I will round round down and when you round down be careful doesn't mean you decrease this too it literally means you just only have the two just get rid of everything after it so it becomes twenty four thousand two hundred that's the process where you round down if you round up becomes twenty four thousand three hundred and it makes sense twenty four thousand two hundred and forty nine is going to be sitting right over here someplace so it's going to be closer to twenty four thousand two hundred twenty four thousand two hundred would be the nearest hundred when we round down in this case for the case of the problem twenty four thousand two hundred and fifty nine the nearest hundred is twenty four thousand three hundred we round up