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### Course: 4th grade > Unit 5

Lesson 5: Estimate quotients# Estimating quotients

Sal uses estimation to determine if quotients are reasonable or unreasonable.

## Want to join the conversation?

- "At3:45Sal used 6000 instead of 6,200 it was kind of confusing because the estimated value that he used earlier and only changed on the first question was on the hundreds place but on that part it was now the whole value. He changed the value of thousands. Is it possible that we can choose either one of those?"(16 votes)
- See in this you just have to use your time tables.

2400 is used as in 3's time table 3x6 is 24. Same way in 6000. There is no 62 unless you multiply on and on.(4 votes)

- Answers: unreasonable ,reasonable, unreasonable.(13 votes)
- hey may i ask whats a the reasonable and unreasonable means ?(7 votes)
- Reasonable means If it could be or has a reason for the estimate to be like that and unreasonable is jurist the opposite.(7 votes)

- This is a cool video for estimating quotients. It helped me a lot in class.(5 votes)
- I am kinda confused why dident he use 6200 instead of 6000?(4 votes)
- Question: At1:13-1:39why estimate 2419 to 2400 and not 2000? Is it because 2400 is closer to estimate than 2000?(4 votes)
- sal is so good at expalaning(3 votes)
- why did he round 6219 to 6200 but he rounds 6202 to 6000. Do it the same way not different!(2 votes)
- He rounded it to 6000 because the question was 6219 divided by 2, but he needed to round it to 6000 because you can't divide 9 into 2 or 1 into 2, so he had to get read of 1 and 9, but I don't know why he got read of the 2 though? But so he can do the right problem. 6000 divided by 2 = 3000 not 300. So, he did that to know the answer was reasonable or not. Hope this helps you!(2 votes)

- I looked up something on Google & figured out that numbers cannot get bigger by using division.(2 votes)

## Video transcript

- [Instructor] 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. Someone is estimating that
2,419 divided by three is roughly equal to 7,500 and 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. 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. The way that I'd like to tackle this is just try to do the estimation myself. I'll start with this first one. 2,419 divided by three. One way to estimate is try to think about what
numbers are these close to that are a little bit
easier to compute with. 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. 2,419, well it's a little
bit more complicated. But I could try to think of is there there a multiple of
three that's close to 2,419 that is a fairly friendly number? I do know that three times eight 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 three. So I could say that
this is roughly equal to 2,400 divided by three. All I did is I said, hey
2,419 for estimation purposes let's just say it's
roughly equal to 2,400. And then 2,400 is fairly
straightforward to divide by three. This over here 24 divided by three is eight so 2,400 divided by three is 800. This is going to be 800. So 2,419 divided by three
should be roughly around 800. 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 almost 10 times more than 800 so, this I would say is unreasonable. All right, let's think about this next one and again, pause the video and see if you can have a go at it. All right, I'm just going
to try to estimate again. So 435 divided by five. Let's say that's roughly equal to. An easy multiple of
five that's close to 435 if I wanna think of a friendly number it might be 400. So I'll say that's roughly
equal to 400 divided by five. Now, we know that 40 divided by five is is eight, sorry. And so 40 10s divided
by five is eight 10s. So this is going to be equal to 80. And you could think
about it the other way. Five times eight 10s is going to be 40 10s which is the same thing as 400. 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. Pause the video again, see
if you can have a go at that. All right, so we have
6,202 divided by two. We could say that's approximately equal to or roughly equal to. Well, if I just wanted
to do it very roughly I could say, hey 6,202 let's just go to 6,000 just to make things really easy. Divided by two. And so this is going to be
six 1000s divided by two would be three 1000s or 3,000. But here they have 300. That's one tenth of what I have over here. So this is unreasonable. And we're done.