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Ratios, Percentages, and Proportions Videos 55 videos

SAT Math 10.3 Geometry and Measurement
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Converting Percents to Decimals 2408 Views


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Description:

Converting percents to decimals is easy: just move the decimal point two to the left. Yep, that's it. To the left, to the left... convertin' those decimals into percents .

Language:
English Language

Transcript

00:07

Converting Decimals, Percents, and Fractions, a la Shmoop.

00:11

You could think of decimals, percents, and fractions as three different languages for

00:15

numbers. Naturally, you sometimes need to translate

00:17

from one language to another. And lucky you, we’re here to help.

00:21

This is where conversion comes in. Conversion is the time-honored Western tradition

00:26

of forcing others to believe exactly the same things that you do.

00:30

Actually, we’re talking about converting one “language” of a number into another.

00:35

For example, your “friend” got detention two out of five days this week.

00:39

That scenario could be expressed as a fraction. Or it could be expressed as a frantic exclamation,

00:45

as in: <<DS voice>> “My parents are going to kill me!”

00:49

Or we could turn it into a percentage, by calculating how many detentions your friend

00:53

is on pace for over the course of 100 days. Remember, percent really means “per hundred.”

01:00

Five times twenty equals one hundred, so we also multiply two times twenty, which equals

01:05

forty. Now we have forty over one hundred, or forty

01:09

percent. That 40% detention rate could also be expressed

01:12

as 40 point zero percent. When you start listing your detention percentage

01:17

with a decimal point, it may be a wake up call to get some help.

01:21

To convert forty percent into a decimal, we simply move the decimal point two places to

01:26

the left. This gives us the decimal zero point four.

01:29

Great batting average. So two-fifths equals forty percent equals

01:34

zero point four. Let’s try a quick drill.

01:37

What percent is zero point nine? Ninety percent. Good free throw percentage

01:42

for basketball. Bad survival rate for appendectomies. Now let’s turn it into a fraction.

01:48

Since percent means per hundred, we know ninety percent is really ninety out of one hundred.

01:53

We can reduce it to make everything nice and neat.

01:57

Ninety and one hundred can both be divided by ten, giving us nine-tenths.

02:02

Are you fluent in decimals, percents, and fractions yet?

02:04

Don’t worry if you’re only 50% of the way there.

02:16

In that case, you only have 60% more to go. Wait…

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