Converting Percents to Decimals

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.

LanguageEnglish Language
Ratios, Percentages, and ProportionsPercents

Transcript

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…