Math Antics - What Are Percentages? - Free Educational videos for Students in K-12

Math Antics - What Are Percentages? - By mathantics

Transcript


00:03	Uh huh . Hi . Welcome to Math Antics .
00:08	Now that you know all about fractions from watching all
00:10	of our fractions videos , it's time to learn about
00:13	something called percentages . Percentages are super important . Have
00:17	you ever been in a math class and heard another
00:19	student as a teacher ? Um Excuse me , A
00:22	teacher . When are we ever gonna use this stuff
00:26	? You know like in real life ? Well ,
00:31	when it comes to percentages , the answer is 100
00:34	of the time . All right . Maybe not 100
00:37	of the time , but a lot percentages are used
00:41	every day to calculate things like , well , how
00:43	much sales tax you pay when you buy something ,
00:45	how much something costs when it's on sale . How
00:48	much fibers in your granola bar or how much money
00:51	you can make if you invested in the stock market
00:53	. That's all real life stuff . For sure .
00:55	So you can see that it's really important to understand
00:57	percentages and how we use them in math . All
01:00	right , then . Are you ready to learn the
01:02	key to understanding percentages or percent says they're called for
01:05	short drumroll , please ? A percent is a fraction
01:09	What ? That's right . A is a fraction .
01:13	And since you already know all about fractions , learning
01:16	about percent is going to be easy . But a
01:18	percent isn't just any old fraction of a percent is
01:21	a special fraction that always has 100 as the bottom
01:25	number . If it's a percent , the no matter
01:27	what the top number is , the bottom number will
01:30	be 100 . In fact , because the bottom number
01:33	of a percent is always 100 . We don't even
01:35	write it instead . We use this handy little symbol
01:38	called a percent sign . Whenever you see this symbol
01:41	after a number , it means the number is a
01:43	percent . It's really a fraction with 100 on the
01:46	bottom . But it's just being written in this more
01:48	compact form like this number 15 here it's got the
01:52	percent sign after it . So we read it as
01:54	15% . And because the percent is really a fraction
01:58	that always has 100 as the bottom number . We
02:00	know that it means the same thing as 15 over
02:03	100% . Make even more sense if you know what
02:06	the word percent means . The prefix of the word
02:09	per means for each or for every you know like
02:13	if someone said only one cookie per person and the
02:16	root word sent is Latin for 100 . That's why
02:19	there's 100 cents on the dollar . So percent literally
02:23	means per 100 And that's why they're shortcuts for writing
02:27	fractions that have 100 as the bottom number . All
02:31	right then . So whenever you see a percent like
02:33	this , you know it can be replaced with or
02:35	converted to a fraction . Let's look at a few
02:38	examples . So you see the pattern . three means
02:42	3 over 100 . 10 means 10 over 125 means
02:47	25 over 175 means 75 over 100 . These are
02:53	percents . And these are the fractions that they stand
02:56	for . There's a few other interesting percent that we
02:58	should take a look at like this 1 0% .
03:02	Can you have 0% ? Yes , 0% . Would
03:06	just mean zero over 100 . It's what we like
03:09	to call a zero fraction because its value is just
03:11	zero . Remember ? It's okay to have zero on
03:14	the top of a fraction , but not the bottom
03:16	. All right then . What about 100% ? Well
03:20	, 100 just means 100 over 100 . That's what
03:23	we like to call a whole fraction . The top
03:25	number is the same as the bottom . So its
03:28	value is just one hole or one . Okay ,
03:31	then 0% is just zero and 100% is just one
03:35	. But what about numbers bigger than 100 ? Can
03:37	you have 100 and 26% yep . It works exactly
03:41	the same way . 100 and 26% Just means 126
03:45	over 100 . And you know , from the fractions
03:48	videos , That's what we call an improper fraction .
03:51	The top number is bigger than the bottom number .
03:53	So the fractions value will be greater than one .
03:56	All right , team . I want you to go
03:58	out there and give me 110 effort in today's game
04:02	. But coach , it would be improper for us
04:04	to give 110 effort in today's game . Okay ,
04:08	so now , you know the key to percentages that
04:11	they're just special fractions that always have 100 as the
04:14	bottom number . But there's one more thing that I
04:16	need to tell you about in this video and that's
04:18	decimals . Do you remember in the video about fractions
04:22	and decimals that you can convert any fraction into its
04:24	decimal value ? Sometimes it was kind of tricky converting
04:28	to a decimal if we had to divide the top
04:30	number by the bottom number . But other times like
04:33	when we had based 10 fractions , it was easy
04:35	because decimal number of places are made for counting based
04:38	infractions like 10th , hundreds and thousands . Well guess
04:42	what percents are based infractions there ? Hundreds because they're
04:46	bottom number is always 100 . That means it's really
04:50	easy to rewrite a percentage as a decimal number .
04:52	You can do it the same way as we did
04:54	in the base 10 fractions video for example , we
04:57	know that 15 is just 15 over 100 . Right
05:01	? That's it's fraction form But it also has a
05:03	decimal form . 0.15 . Because this is the hundreds
05:07	place and 0.15 means 1500s . So we can rewrite
05:14	15 as a fraction 15/00 or as a decimal 0.15
05:20	. And now that you know why we can easily
05:22	convert a percentage to a decimal . Let me show
05:25	you a really simple trick for doing it . First
05:28	you start with the number in form like this .
05:31	35% . Next you imagine where the decimal point should
05:35	be in the number 35 . It's not shown .
05:38	But if it was it would be right here next
05:40	to the ones place now . Remember 35 and 35.0
05:44	are the same value . Now that you know where
05:47	the decimal point is . Just move it to number
05:49	of places to the left away from the percent symbol
05:52	and draw it in right there . Last of all
05:55	, once you've moved the decimal point you erase the
05:58	percent sign because you don't have a percent anymore .
06:01	Moving the decimal .2 places to the left , converted
06:04	it into the decimal value of that% . Let's try
06:08	converting a few more percents into their decimal values .
06:11	So you can get the hang of it For 62%
06:14	. We move the decimal .2 places to the left
06:17	and get 0.62 . Remember we can put an extra
06:20	zero in front of the decimal point to be a
06:22	placeholder . And to make the decimal point easier to
06:25	notice for 75 we move the decimal point and get
06:29	0.75 for 99% . We move the decimal point to
06:33	get 0.99 . Pretty cool . Huh ? Okay .
06:37	But what about 4% ? You might wonder how we
06:40	can move the decimal point to places over when our
06:43	number only has one digit . But all we need
06:45	to do is use zero as a placeholder in the
06:48	number of place that's missing . Then when we move
06:51	the decimal point to places over , we end up
06:53	with a decimal value of 0.04 . Now that makes
06:57	sense because four is in the hundreds place and four
07:01	is for over a 100 And in the same way
07:04	one would just be 0.01 . Again we need that
07:08	extra zero placeholder . Here's a few more interesting examples
07:12	. zero would just be 0.00 . And if we
07:17	have 100 and we move the decimal .2 places to
07:20	the left , we end up with 1.00 . But
07:24	1.00 is the same value as one . And that's
07:28	why 100 represents one whole . And if we have
07:31	142% , we move the decimal point to get 1.42
07:36	, That's a value greater than one . Which is
07:38	what we would expect . Because 142 is really an
07:42	improper fraction . 142 over 100 . Its value should
07:46	be greater than one . All right . So now
07:49	, you know that a percent is a special fraction
07:51	that always has 100 as the bottom number . And
07:54	you know that you can rewrite percents in either their
07:56	fraction form or their decimal form . 25 is 25
08:00	over 100 or 0.25 . But keep in mind that
08:05	you could go the other way too . If someone
08:07	gives you a fraction with 100 as the bottom number
08:10	, you can rewrite it in percent form . If
08:13	you get 12 over 100 you can say that's 12%
08:16	. And if you get 80 over 100 you can
08:18	say that's 80% . Or if you get the decimal
08:21	0.10 you can say that's 10% . And if you
08:25	get the decimal 0.38 you can say that's 38% .
08:29	So that's the key to percentage . Is there another
08:32	way to write fractions and decimals ? But there's a
08:34	lot more to learn about how they're used in math
08:36	and we'll learn more about that in the next few
08:38	videos . But for now you should be sure that
08:41	you really understand the basics of percentages by doing the
08:44	exercises for this section . Thanks for watching Math Antics
08:47	and I'll see you next time . Learn more at
08:51	Math Antics dot com .

Summarizer

DESCRIPTION:

OVERVIEW:

Math Antics - What Are Percentages? is a free educational video by mathantics.

This page not only allows students and teachers view Math Antics - What Are Percentages? videos but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.