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g'day welcome to tech math Channel what
we're gonna be having a look at in this
video is a way of working the square
root out of numbers these are going to
be looking where we've got the square
perfect squares that are occurring less
than 100 but we haven't with these out
in just seconds
okay so I'll show you how to do this
anyway so first off we'll give you an
example so how fast can you work at the
square root of 576 I'll give you a
couple of seconds okay times up
yeah did you get the answer of positive
or minus 24 if you did that's that's
that's great you got the right answer
there if not I'm gonna show you how to
through these you know just by the way
before I get any further the square root
iya it's really important that you
actually identify this as a positive or
negative answer because say negative 24
times negative 24 gives us the answer
526 the same way 24 times 24 gives us Y
an answer of 576 so just before I go on
just just make a note of that
having said that I'm probably not gonna
worry about doing the positive and minus
for the the rest of these numbers here
I'm just gonna put them down as numbers
and you can assume that there's a
positive or minus there so I'm gonna
show you how we do this and it's going
to involve knowing your squares all the
way up to I've done it up to nine
because I think you should probably know
it N squared I think you should know
these already anyway I think probably
most of you will but you're gonna see
that I've got to shot it down here the
squares 1 squared is 1 2 squared is 4 3
squared is 9 4 squared is 16 and so on
and so forth we're gonna be using these
a fair bit you're also going to notice
first off that I've actually uh put the
units of these in a different color I'm
just gonna draw your attention to those
actually right now we'll be first are
working out our answer here so why don't
we do it is as follows the way we work
at square root of 576 using this is as
follows okay so
first thing we do is we have a look at
this particular units answer the number
here the Kahless six and we're looking
for a square root here the corresponds
to this or a square sorry it's square
that corresponds to this so 16 does and
36 does the square root that goes
alongside of those we have 4 when we're
talking about our 16 and we have 6 when
we're talking about 36 so we're answer
is going to finish you know 4 or 6 and
we're gonna work out for sure which one
this is in a little second but first off
we have to work out now ere are our
first digit so I'm gonna cross out
there's two digits that's next thing you
do and we just still directly now with
this five okay yeah we're gonna have a
look here along here in ear square
answers here we're looking for a number
that flickers just below five so it's
only gonna be the number five itself or
the one closest to five which is under
okay so gonna go along here and you can
see one four fours just under five and
nines too much so we're gonna be dealing
with this for now the square root of
four is two twos the first part of our
answer
okay now we're always there now we have
to just working out whether or not we're
dealing with is it 24 or 26 is our
answer and the way we do this as follows
is we get out to here and we just
multiply by the next number up okay and
I mean the next number up from 2 which
is 3 so 2 times 3 equals 6 now we have a
look at this 6 and pretty much what we
do is as follows it is 5 here is less
than this 6 we choose the lesser number
okay
if it was more we choose the bigger
number okay so 2 times 3 is 6 5 is less
than 6 so we choose the lesser number
here so we're answer it's 24
okay that's a bit of going through I'll
tell you what we'll go through a couple
more of these you'll pick them up as we
go along and then what I recommend is
you probably are be able to start
pausing it and giving it a go okay so
let's get into another one of these so
what about we do 1849 are we gonna work
out the square root of this so first off
once again what we do is we're looking
at this diet here okay they died and the
number that goes along without knowing
could either be a three or a seven
you notice these complimentary numbers
add up to 10 to it so it's kind of a
handy little thing the next thing I do
is I cross out these two numbers
okay so answers gonna finish it a three
or a seven now I look at this 18 so 18
and I go down here and I'm looking and
16 just occurs below 18 25 too much so
the square root of 16 is 4 the first
part of our answer is 4 okay 4 times 5
okay
4 times 5 is 20 and now I compare this
to 18 here so 18 as you'll see is less
than 20 so we choose once again the
lesser number okay so we're answer is 43
you get faster and faster and faster of
these okay keep practicing them you will
get used to doing them okay okay what
about one more of these are 3364 okay
pause it give it a go okay so looking at
the last number here it could be either
or two or an eight okay so let's cross
out these two digits here and now what
we do is we are looking for that first
digit okay so it's going to be a five
okay you're probably working that out
really really quickly okay because five
five is twenty five six six is thirty
six that's too much isn't it so let's go
five times six five times six is thirty
33 is bigger then 30 so we're gonna
choose the bigger number we have an
eight
so our answer
is 58 okay what about another one what
about we have a different one here we'll
do
2025 now this is a nice and easy one
you'll see why okay pause it and give it
a go
okay so 2025 you're gonna see that can
only be a 5 at the end here because
there's no other option
okay cross it out and then we're looking
for the number which is going to be
occurring under here okay so 4 squared
is gonna be 16 5 squids too much so it's
going to be a 4 but this Cerreta because
we don't need to differentiate between
whether it's a five or it's at five
isn't it so 45 times 45 that's our
answer
pretty cool right okay couple more of
these just about three more of these
I'll put them out there I recommend them
and see here you go
so five thousand one hundred and eighty
four okay so our last number could
either be a 2 or an 8 okay 7 squared is
49 so this is gonna be a 7 okay
7 times 8 is 56 and 56 is 50 ones less
than 56 so we're going to choose the two
okay
this is how I start doing these in my
head I'm gonna start doing the more and
more like this going to do the rest of
my that I reckon so
what about 1444 okay so the last number
here could be a 2 or it could be an 8
okay so 14 16 squares are for squares
too much three squares good so it's
going to be three three fours are twelve
fourteen greater than 12 so we're gonna
choose the greater number which is an 8
38
all right lucky last one out of all them
is 8281 okay so as you see here 81 well
81 we could I'm on the a look at the
last time here no it's sort of tempting
to go hating one that hey wait a second
that's dying I'm really gonna look at
the last digit here so 81 it could be a
one or a Naaman okay so what we'll do
now is we'll cross that out and 82
okay so 82 yeah once again this is gonna
be annoying okay it's not enough because
that's not necessarily annoying so we've
got nine okay so 9 times 10 is 90 82 is
less than 90 so I'm gonna choose a
lesser value we're gonna 91 anyway what
did you think of that particular trick
there it's that's not a bad trick okay
it does take a bit of getting used to
but once you get used to what it's
actually fairly handy I kind it's a
great little way of working about you
starts me out of work the mount as you
see towards the end much much much much
much faster okay
and yeah you will make the odd mistake
but they everybody does this and now in
a future a couple of videos I am gonna
be looking at about how to work out the
are how to calculate squares of any
number okay the laborious slow out doing
this but it's not the slowest way ever
just a nice little trick for doing these
and something you may or may not know
how to do already you know thanks for
watching see you next time bye
