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Current time:0:00Total duration:4:05

Estimating quotients

CCSS.Math:

Video transcript

we are told to use estimation to tell whether each estimated quotient is reasonable or unreasonable so we have a bunch of estimated quotients here so someone is estimating that 2419 divided by three is roughly equal to 7,500 we have to figure out is that reasonable or unreasonable and then we have two more quotients to figure out if it's unreasonable or reasonable so pause this video and see if you can figure it out on your own before we work through it together all right now let's work through it together and the way that I'd like to tackle this is just try to do the estimation myself so I'll start with this first one so 2419 divided by three well one way to estimate is try to think about what numbers are these close to that are a little bit easier to compute with you some people would say they're a little bit friendlier so to speak well three is already a pretty simple number a pretty friendly number 2419 well it's a little bit more complicated but I could try to think of is there a multiple of three that's close to 2419 that is a fairly friendly number well I do know that 3 times 8 is 24 so if I had something like 2,400 which is the same thing as 2,400 that'd be easy to divide by 3 so I could say that this is roughly equal to 2,400 divided by 3 all I did is I said hey 2419 for estimation purposes let's just say it's roughly equal to 2400 and then 2400 is fairly straightforward and divided by 3 this over here 24 divided by 3 is 8 so 2400 divided by 3 is 800 so this is going to be 800 so 2400 19 divided by 3 should be roughly around 800 now they're saying that it's roughly 7,500 that's a lot more than 800 if they said 750 then I'd say hey that's pretty reasonable but they're saying 7,500 that's all most ten times more than 800 so this I would say is unreasonable all right now let's think about this next one and again pause the video and see if you can have a go at it alright so I'm just going to try to estimate again so four hundred and thirty-five divided by five let's say that's roughly equal to so an easy multiple of five that's close to 435 if I want to think of a friendly number it might be 400 so I'll say that's roughly equal to 400 divided by five and now we know that 40 divided by five is 10 is 8 sorry and so for 40 tens divided by five is eight tens so this is going to be equal to 80 and you could think about it the other way five times eight tens is going to be 40 tens which is the same thing as 400 so this thing should be roughly equal to 80 well that's exactly what we estimated so that feels very reasonable all right this last one so pause the video and see if you can have a go with that all right so we have six thousand two hundred and two and there say divided by two now we could say that's approximately equal to a roughly equal to well if I just want to do it very roughly I could say hey six thousand two hundred and two let's just go to six thousand just to make things really easy divided by two and so this is going to be six thousands divided by 2 would be three thousands or 3,000 but here they have three hundred that's one tenth of what I have over here so this is unreasonable and we're done