Math tip for calculation - Free Educational videos for Students in K-12

Math tip for calculation - By tecmath

Transcript


00:0-1	Good day . Welcome to Tech Math channel . This
00:02	is a quick video looking handy little trick . I
00:03	use also get my students using just sometimes in maths
00:07	when you're not certain how to proceed . I can't
00:09	give you an example like this . It's not much
00:11	of a trick , but it's really , really quite
00:13	effective . So I've been working with trigonometry , my
00:17	students at the moment and we're getting things that come
00:19	out like this , so it's 37 over X is
00:23	equal to 0.14 and they're getting a bit stuck .
00:26	Okay , how are they going to work out X
00:28	. Here , are they going to get this number
00:31	and divided by this number ? This number divided by
00:33	this number . They're gonna multiply these two numbers .
00:35	This trick , I want to show you just alleviates
00:39	that our little uncertainty that you can get with this
00:41	. Another question has been sent in by a listener
00:44	called Rubby protesting thank you for that question . By
00:46	the way , was this one How to go about
00:48	working at say something like 20% Of a certain number
00:53	is equal to 600 . And how would you go
00:56	about for certain ? Working out with this number is
00:58	because people kind of get a little bit bit muddled
01:00	when they're doing these occasionally . So this trick ,
01:03	I'm going to show you this method , I'm going
01:05	to show you is really good for working this out
01:08	. So let's just launch straight into this first example
01:10	here . Okay , so here's my first example here
01:15	, and I'll show you what this trick is .
01:17	It's not much of a trick , but it's really
01:19	, really handy . It pays big dividends and it's
01:21	this , if you don't like the numbers you're being
01:23	given . If these numbers throw you a little bit
01:25	, set up a similar equation with numbers you do
01:28	like with things that you know to be true ,
01:30	I'll show you what I mean . We've got a
01:31	number divided by another number and it's got uh something
01:35	here . Okay , So we could actually set this
01:37	up very similar and I use these particular numbers Six
01:40	divided by three equals two . And the reason I
01:42	use these is they're nice and simple , but the
01:45	numbers are all different . Okay , so we're trying
01:48	to find out X here and this is how I
01:50	now employ this . We're trying to find out X
01:52	which is in the same position as the three here
01:55	. I could set this up and say X is
01:57	equal to or three is going to be equal to
02:00	six divided by two . So we're going to go
02:03	along and do that same pattern here . This number
02:05	divided by this number X is going to be equal
02:07	to 37 Divided by 0.14 , Divided by 0.14 .
02:15	And you know for certain that you've got it in
02:18	the right order then . So 37 divided by 0.14
02:24	, You won't get the answer of 264.29 . Not
02:29	so much after the answer on this one more is
02:31	showing you that method there . So what do you
02:33	think of that ? Okay so it's it's a very
02:35	very simple sort of thing but it's really really quite
02:38	effective and you know for certain really quickly what you're
02:41	going to be doing by the way you like this
02:43	video please hit the like button and make sure you
02:45	subscribe . Just gonna get that quickly and um now
02:48	look almost gonna go to this next example here .
02:51	Okay so for our second example here thanks for that
02:54	Ravi is 20% of a certain number is equal to
02:58	600 . So let's just rewrite this so it's a
03:01	bit nicer because 20% is equal to 20 out of
03:05	100 that's what percent means . So you can work
03:07	this out and decimal is and that's the first thing
03:09	I do . 20 divided by 100 which is equal
03:12	to 0.2 Of in math as times . And we
03:17	have this unknown number , the one we're looking for
03:20	which is equal to 600 . Okay , so now
03:23	what do we do ? Well , I'd set this
03:25	up where I have these numbers once again 32 and
03:28	six you're gonna look and go well one number times
03:30	another number is equal to this . So we could
03:32	use our 3 to 6 we could say three times
03:36	two Is equal to six . We're trying to find
03:39	out the number in the two position here . Okay
03:41	, so there's two here is going to be equal
03:43	to the number in the 6th position , divided by
03:47	the number in the three positions because two divided by
03:50	our two equals six , divided by three . Okay
03:53	, let's just sub these through The number of the
03:55	6th position is 600 . This is now for our
03:58	unknown here , Divided by the number in the three
04:01	position here , which was 0.2 , What's the answer
04:04	? Going to be 600 , divided by 0.2 .
04:08	If you do that , you're going to get the
04:10	answer of 3000 . So that's once again how you
04:14	can use this little method just to know for certain
04:16	what you're doing . Now look this is not a
04:19	trick at all , this is just a method of
04:21	setting things up so they so they make sense .
04:24	And you can you can then compare them to something
04:26	which is like and like sort of thing . Uh
04:29	So what about I give you a couple of examples
04:32	, So X . Over 1 80 equals 50 .
04:35	Now . You might be able to do this straight
04:36	away . But try this using this method is I
04:38	can guarantee occasionally you'll hit this stage of uncertainty .
04:42	So once again six divided by three equals two .
04:46	Okay we're trying to find out the number in this
04:49	sixth position here . So really simple . We're just
04:51	gonna multiply these two numbers . So we're gonna multiply
04:54	these two numbers 180 times 50 . What's the answer
05:00	going to be to work out excess is what X
05:01	. is equal to X . Is going to be
05:04	equal to 9000 . Okay for the second example here
05:11	another one I found students can struggle in the past
05:13	. You have a T . V . has a
05:15	deposit of 8% . You pay down the positive 8%
05:17	deposits , $250 that you pay . What was the
05:21	original price ? Okay so we're gonna set this up
05:24	first off , so we're saying that 8% of The
05:29	actual price , the price that we're looking for is
05:31	equal to $250 . No problem . Right , so
05:35	let's set this up using that little method . Their
05:38	first off . You're gonna actually no , I should
05:40	change this first option because 8% which is eight out
05:43	of 100 8 out of 100 which is equal to
05:47	0.08 . A lot better . We write it like
05:50	that to 0.08 Times a certain number is equal to
05:55	250 . Okey Dokey . Let's uh put that little
06:01	method in that I've been saying . So we're basically
06:03	going okay numbers it line up we could say three
06:06	times two is equal to six . Now we're after
06:10	the number and there's two position here . So two
06:13	is equal to this number , the six ah Divided
06:18	by three . Which for our numbers are known here
06:21	is going to be the number in the 6th position
06:23	. To 50 divided boy . 0.8 , 0.08 .
06:30	Sorry . Making mistakes . So what's the answer going
06:33	to be here ? Uh the original price is going
06:36	to be 2500 And $62 And 50 cents . I
06:42	probably should put a dollars there . That's what it's
06:44	equal to . Okay . Anyway , hopefully that video
06:48	is of some help . Okay , it's not a
06:50	major trick . It's just a little method I use
06:52	occasionally to try and sort out uncertainties once again ,
06:55	thanks for that question . Uh Anyway , if you
06:58	like this video I said just poked the like button
07:01	. Be really gentle with this time . It's been
07:03	getting a bit of a working out maybe lately .
07:04	Okay , So just be really , really gentle with
07:07	the like button , but make sure you hit it
07:09	anyway . Thanks for watching . We'll see you next
07:11	time . Bye .

Summarizer

DESCRIPTION:

OVERVIEW:

Math tip for calculation is a free educational video by tecmath.

This page not only allows students and teachers view Math tip for calculation videos but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.