yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Example using estimation for decimal products


2m read
·Nov 10, 2024

We are told that 52 times 762 is equal to 39,624, and then we're told to match each expression to its product. These products, this is the exercise on Khan Academy. You can move them around so the product can be matched to the appropriate expression. So pause this video and see if you can figure that out.

All right, now what you might have realized is all of these expressions deal with the same digits as 52 times 762. They just have the decimal in different places. So what we can do is we can say, "Hey, look, the answer is going to have the digits 39624 in that order." You could see all of these have the digits 3, 9, 6, 2, 4 in that order.

Then we can estimate what these expressions should be equal to, what the product should be equal to, to think about the decimal. So this first expression, 0.52 times 76.2, the way I think about it is 0.52, that's close to 50 hundredths. That's close to a half, and so 76.2, that's close to 76.

And so this first expression, this first product should be roughly half of 76. Half of 76 would be around 38, and so which of these is close to 38? Well, this first one is 39.624, so that's actually the closest to 38. The second one is 396, and then we have 3962.

So I like this first one, the 39.624. That feels right. Now the second expression, 0.52 times 760, well once again, 0.52 is roughly equal to 50 hundredths, roughly equal to 5 tenths, roughly equal to one half. And so, and 762, we could say, "Hey, you know that's if we want to be really rough, really, really approximate it, we could say hey it's roughly 800."

And so this should be about half of 800, so it should be around 400. And so we actually had that choice already there, so this would be 396.24. It definitely wouldn't be the 3962.4, and so I'm already feeling good that this last choice sits down here.

But I can verify it; 5.2, well let's just say that's roughly 5. 762, let's say that's roughly 800. So 5 times 800, that would be around, that would be 4,000. And so we would expect this expression to be close to 4,000, and indeed that's what this choice is.

So it turns out that it was already in the order that we needed it to be, but it's good that we checked on that.

More Articles

View All
The Danger and Excitement of Underwater Cave Diving | Short Film Showcase
We come here every winter, bringing tons of dive stuff, going into the mountains. During this expedition, Darrell, we get to explore this cave system that we have found here. This is the longest underwater cave in Sweden, and we know there’s going to be s…
Climbing Islands in the Sky in Search of New Species | Nat Geo Live
Mark: My years in Yosemite were the best years of my life. That was where I was training and I was learning the skills of big wall climbing. And I wanted to find walls that people hadn’t done before and I wanted to pioneer my own routes. But, you know wha…
Adaptation and environmental change | Mechanisms of evolution | High school biology | Khan Academy
Hi everybody, Dr. Sammy here, your friendly neighborhood entomologist. Here to talk to you about how adaptation, which is dependent on the environment, responds in the context of environmental change. Natural selection promotes adaptation in populations. …
Making $1000 Per Day as a Master Sushi Chef | Undercover Millionaire
What’s up you guys, it’s Graham here. So have you ever wondered how a private chef is able to charge all the way up to $8,000 a night? Well today, I have you covered because I’m trying one of the most unbelievable side hustles that I have ever seen: learn…
The 3 Pillars Of Stoicism Explained
If we look at Stoicism as a philosophical system, we can divide it in three pillars: Ethics, Logic and Physics. Some scholars arrange these aspects of Stoicism in the form of an egg. The yolk represents the Physics; the white, the Ethics; and the shell th…
United Kingdom vs Great Britain vs England primer
For someone who lives outside of the United Kingdom, the terms United Kingdom and Great Britain and England often feel interchangeable, and they feel like they’re referring to the same thing. But as we’ll see in this video, they aren’t referring to exactl…