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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.

Language:
English Language

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

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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