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

Estimate multiplying multi digit numbers


2m read
·Nov 11, 2024

What I would like to do in this video is get some practice estimating the product of multi-digit numbers, and there's just no better way of getting practice than just trying it ourselves.

So, right over here, it says estimate 29 times 3198. Why don't you pause this video and try to estimate this? Of course, you can do this by multiplying this out on paper or using a calculator, but this is a useful skill. Try to do it in your head; see if you can estimate what this is going to be.

Well, before even looking at these answers, I would say this is going to be approximately equal to... Let's see, 29 is awfully close to 30, and then I could multiply that times... I could either multiply that times 3200, which is awfully close to 3198, or if I want an even more rough approximation, I could say that's roughly equal to 30 times 3,000.

So, if I did 30 times 3,000, 3 times 3 is equal to 9, and then I have one, two, three, four zeros. One, two, three, four zeros! And actually, my approximation, it turns out, is here right over here: 90,000.

Now, if I wanted a slightly better approximation, I could have said this is approximately equal to 30 times 3200. This you could also do in your head. You could say, well, what is 3 times 32? Well, that is going to be 96, and then you have one, two, three zeros. One, two, three zeros! So this would be a slightly better approximation, and if this is what you got, the closest answer here is still going to be equal to 90,000.

Let's do another example. So here we are asked to estimate 137 times 18. So pause this video again and see if you can come up with an estimate; try to do it in your head.

Well, there's once again many ways of trying to tackle it. The way I would tackle it, I would say, well, that's pretty close to 140 times 20, and then this would be equal to 14 times 2 is 28, and then we have two zeros here, so that would be roughly 2800. But when I look over here, there is no 2800, and so maybe the closest one right over here is 2,000.

So that could be an approximation. Another way... it looks actually the way that they did it is they even did a coarser approximation. They rounded this to the nearest hundred, and so they said this is approximately equal to 100 times... and they rounded this to the nearest 10: 100 times 20, which is even easier to do in your head, which is equal to 2000, which is this choice that they got right over here.

More Articles

View All
Ruchi Sanghvi on Sweating the Details
So after about a year of working on Cove, it was the best year ever because I learned the most. Cove was acquired by Dropbox. We wanted to build at scale, and Dropbox gave us a bigger stage to do just that. We loved the people, and we loved the product, a…
From TV Repairman to Artist, One Man Makes Art Out of Parts | Short Film Showcase
[Music] I saw a video once, and it showed the house of the future: TV set in the refrigerator, TV set in the counter, TV set everywhere. You know, controls for this, for that. There I thought, oh, this is funny. You’d have to have another room in the hous…
Why Die?
When do you want to die? The Reaper is busy, but he can fit you in right now. Too soon? Later, perhaps? Future you will keep the appointment? Old and with a life fully lived, perhaps ever so slightly bored and ready? Now you might think that, but when th…
Civil society | Citizenship | High school civics | Khan Academy
Civil society is one of those terms that you might hear in a politician’s speech, maybe in a line about the importance of maintaining a strong relationship between the government and civil society. But what does it actually mean? A society that’s civilize…
If you can't focus, please watch this video…
Do you know why your brain is like a browser with too many tabs open? What if I told you that you’re just one funny cat video away from losing your focus completely? In this video, I will dive into a major culprit of focus. By the end of this video, you’l…
How Does The James Webb Space Telescope Work? - Smarter Every Day 262
This is my dad, and he’s about to finish this major job you’ve been working on, which is the James Webb Space Telescope? Sun shield for the James Webb Space Telescope. Hey, it’s me, Destin, welcome back to Smarter Every Day. The James Webb Space Telescope…