Locating large numbers on a number line
About this video
The video places 145, 1,450, 14,500 and 145,000 on a number line from 0 to 200,000. By halving to find benchmarks like 25,000, 12,500 and about 3,125, it shows that 145 and 1,450 sit almost at zero, 14,500 is just past 12,500, and 145,000 is just left of 150,000. Each number is 10 times the one before.
You'll be able to
- use benchmark numbers to estimate where a large number goes on a number line.
- explain why small numbers look close to zero on a very long number line.
- notice that each number in 145, 1,450, 14,500, 145,000 is 10 times the one before.
Key words
- number line
- A line with numbers placed in order at equal spacing.
- benchmark
- A helpful reference number on a number line, like halfway points.
- estimate
- To find a close, sensible position or value without being exact.
Transcript
- [Instructor] What we have here is a number line that goes from zero to 200,000, and what we're gonna do is try to plot four different numbers on this number line. So we're gonna try to plot the number 145, and I'm gonna do it all in different colors. We're gonna plot the number 1,450, we are going to plot the number 14,500, and last but not least, we are going to plot the number, lemme just in a new color, 145,000.
So if you feel like it, pause this video, and just at least think about where you would put these numbers, and you could even point at them with your finger if you don't feel like taking pencil and paper out. Okay, now let's do this together. So let's start with 145.
It seems like a pretty big number until you look at this number line, which is going in all the way to 200,000, so let's just think about where 145 would be. This is zero, this is 50,000, so half of this, this right over here, I'll mark it up a little bit more, that would be 25,000.
Half of that, if I go right over here, let me do that, this is about closer to half, that would be about 12,500, and so 145, even 1,000, if I were to say this right over here, that would be, let me get a little bit closer to halfway of that, so right around there, that would be 6,250.
So you can see, even if I were to go here, this little thing right over here, that's going to be 3,125, so that one right over there, roughly, is 3,125. So where would 145 be? Well, on this number line, it would look awfully close to zero, even though it's a pretty big number, this number line is so big, this gets us pretty close to zero.
That's where the 145 is. And not only the 145, where would the 1,450 be? Well, I just said this thing over here is 3,125, so 1,450 is going to be not even half of that, so it's going to be right over there. That's where 1,450 is, and then we have 14,500, and you might have noticed that each of these are 10 times the last one.
So 14,500, well, this might get a little bit more breathing room, but not much, 'cause if this is 12,500, and then this is going to be around 20,000, so 14,500 is only 2,000 more than this, so it's going to be right around, or 2,000 more than 12,500, so it's gonna be right around there, so still pretty close to the left side of this number line.
And then last but not least, 145,000. Well, that's going to be, that's only 5,000 less than 150,000, so just eyeballing it, that's about right over there. So even though, in our everyday lives, all of these numbers feel big, when you have a number line that's this big, you appreciate how much larger 145,000 is than even 14,500, and then it's a lot larger than these other ones that we have here on the left.
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