How to square any numbers in your head - fast mental math trick - Free Educational videos for Students in K-12

How to square any numbers in your head - fast mental math trick - By tecmath

Transcript


00:0-1	Good day . Welcome to the Tech Math channel .
00:02	What we're going to be having a look at in
00:03	this video is a way of squaring any two digit
00:06	number . That is a way of multiplying any two
00:09	digit number by itself fairly instantly . Okay , so
00:12	sit back and enjoy , Yeah , I'll give you
00:16	an example to start off . So how fast can
00:17	you do ? 32 squared ? I'll give you five
00:22	seconds . Okay . Time's pretty much up . Okay
00:28	, hopeful . The answer that you get is 1,024
00:32	and if you did , if you got that ,
00:33	that's pretty cool . Right . That's that's pretty impressive
00:36	. Congratulations . That's correct . If you didn't ,
00:39	don't worry , I'm going to show you a way
00:40	of working this out . Okay ? So sit back
00:43	and you'll pick this up pretty quickly . Now ,
00:46	a couple of steps involved in doing this . The
00:48	first one , what we do is we find the
00:50	distance . Well , look at this number here ,
00:52	the number being squared obviously . And we before the
00:57	distance between this number and the nearest tens number .
01:00	Okay , so the nearest tens number 2 32 is
01:03	30 . So the distance between 32 and 30 is
01:06	too okay . Yeah , that's the first step .
01:10	This is something you can do usually do pretty quickly
01:12	. Okay , now we use this to for pretty
01:15	much every step that we're going to be going on
01:16	with now . Okay , the first thing we do
01:18	is we take this to away from 32 To get
01:21	30 and we add this to to 32 to get
01:24	34 . This is all stuff you can do in
01:26	your head pretty quickly . Okay ? We're going to
01:30	get these numbers and multiply them . This is the
01:32	biggest step . Okay , so this is the same
01:35	as sort of like three times 34 with an extra
01:38	zero on top . So we're gonna be going 30
01:41	times 30 which is 904 times 30 which is 1
01:44	20 So 1000 and 20 . Okay . So we
01:51	multiply is that we get 1020 and the very last
01:55	thing we do is we just add the square of
01:57	this number . This no , this difference number two
02:00	. Our answer . So two squared is four .
02:03	We're gonna add these together . And if we do
02:05	we get our answer here . 1,024 . Okay .
02:08	So I'll just go through the steps again . We
02:10	find the distance between this number and the nearest tens
02:13	number , the number being squared , which is to
02:15	we take this number away from the number being square
02:18	we added to the number being squared , so 30
02:20	times 34 and then we add this that was squared
02:25	to our result . Okay , It's not too bad
02:28	. Okay , give it a few guys and you
02:31	will get really really quick at doing this . Obviously
02:33	some are going to be a little bit harder than
02:34	others but it works for all numbers . There are
02:37	two digits . So what about I'd give a few
02:40	examples here . Oh go just a little bit uh
02:43	go a little bit harder now . What about we
02:45	do 33 squared . So what about you pause this
02:51	and work through this ? Or you work through this
02:53	with me ? And then you pause if you later
02:54	ones . So the first step we're gonna do is
02:58	the distance between this and the nearest tens . Number
03:00	10 . Number 30 . So the difference is three
03:04	We take it away we add it to okay so
03:06	we take this away from 33 , we get 30
03:10	, We add this to 33 and we get the
03:12	answer of 36 . Next step Here we multiply these
03:16	so 30 times 36 . This is pretty much the
03:20	same as 900 plus 180 . So 1080 . Okay
03:28	30 times 30 906 times 30 uh 18 . So
03:32	we're going to add that on which was 1 80
03:34	. Okay . The last step is we add This
03:40	number square to it . So three threes and I
03:44	. So what's the answer ? 1000 and IT .
03:48	knowing hey not too bad . Right this is obviously
03:52	the hardest step just here . So that's something you'll
03:55	have to get used to look . I do have
03:57	a video where I look at how to multiply these
03:59	out fairly quickly these answers . So what about I
04:02	do A bit of a harder one will do 77
04:07	squared . Can I ? We've got a few lines
04:11	there . Someone's commented that they really like people do
04:13	that . Don't worry , that's probably the only time
04:15	I'll do it . Um Yeah . Mhm . How
04:20	do we do this now ? So we look for
04:22	the nearest tens number . Okay . The nearest 10
04:24	numbers 80 where ? Three away Okay , so we
04:28	take this away from 77 , we've got 74 and
04:33	if we add this to 77 we have Heidi .
04:37	So let's multiply these numbers out . Okay , if
04:40	we do this 78 to 56 48 to 32 .
04:43	So pretty much we're going to get 560 plus 32
04:47	. So that's going to be +592 with a happy
04:53	little zero on the end because of this . Okay
04:55	, now what we're gonna do this just add three
04:57	squared , so three squared is nine , answer 5929
05:06	. Anyway , how'd you go with those ? Hopefully
05:08	you find that really , really great little trick .
05:10	I think it's a really , really awesome little trick
05:12	, that one . Um Anyway , let me know
05:16	, sending comments and a question , anything like that
05:19	, and I'll speak to you next time I see
05:21	you then , Bye .

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