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Math 4: Round and Round We Go 89 Views
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Description:
Rounding is the process of approximating a number by increasing or decreasing it slightly. It's something you want to do up when invoicing for work but down when calculating a tip.
Transcript
- 00:13
You probably have some friends who tend to exaggerate. [Two people walking down a school corridor]
- 00:17
For example, they may overstate their height... Or maybe they claim to have the same vocal range as Ariana Grande [Guy singing badly on a stage]
- 00:22
Before we move on check your ears and make sure they're not bleeding... [Guy pulls a Starburts out his ear]
- 00:26
In normal life, this sort of exaggerating isn’t always welcome. [Kids sat on a bus]
- 00:29
But in math, there’s always a totally acceptable way of making something seem a
Full Transcript
- 00:33
little more or a little less than it actually is. [Gorilla is driving the bus]
- 00:35
We call it rounding.
- 00:37
Rounding means to approximate a number by increasing or decreasing it slightly. [Coop pointing at the blackboard]
- 00:41
So how does it work, well first we look at the number and find the place value we’re rounding to…
- 00:44
Then we look at the number to the right.
- 00:47
If that number is five or more, we round up. [Up arrow appears]
- 00:49
If the number is four or less…
- 00:51
… we round down. [Down arrow appears]
- 00:53
You can use this cool mathmatical magic everywhere.
- 00:56
You can round height, time, weight and so many other numbers.
- 00:59
Probably not to your credit card bill though, don't push your luck. [Woman walking up to a bank desk]
- 01:01
So how might this work in the real world.
- 01:03
Well if you want a new video game that costs $67 dollars… [Poster for a video game]
- 01:07
… and your mom say she’s not paying seventy dollars for a video game, she’s rounding up. [Kid looks annoyed]
- 01:11
Of course, if the game goes on sale and now only costs $64…
- 01:14
You can totally try to convince her to buy it by rounding down and saying it’s “only [Game sale poster at Christmas]
- 01:19
sixty bucks.”
- 01:20
You never know, it might work… [Mom says maybe Santa can afford it]
- 01:22
Last thing: if you’re ever in doubt about which way to round – up or down – there’s
- 01:26
a quick rhyme that’ll help you remember. [Teacher walks to the front of a class]
- 01:28
It goes like this:
- 01:29
“Five or more, raise the score; four or less, let it rest.”
- 01:32
Catchy, right? Well, we liked it anyway... [Students look unimpressed]
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