Singapore Math: Grade 3a; Unit 1 (part 3) Video Lecture | Mathematics Lesson for Grade 3 (Singapore) - Personal Learning

welcome back well just now we learned
how to say these four digit numbers and
let's just do a little bit of review so
I had written down this number this was
if I just write the digits it's five
nine nine eight and we learned how did
we say this well this says this is the
thousands place it's is five thousand
this is a hundreds place
five thousand nine hundred this is the
tens place so that's 99 tens is nine
he's so 5990 and then this was one place
just eight so this is five thousand nine
hundred ninety eight and we also learned
how to say this number and how do we say
it well there's six and a thousands
place so that's six thousand there's
nothing in the hunters place so we just
ignored it there's ten here 110 so we
could have said six thousand ten too but
that just doesn't sound right or that
that's just not how we say numbers in
English and then this is a bit of an
inconsistent pattern that's six thousand
and twelve so hopefully you have a sense
of that so what I'm gonna give you I'm
gonna challenge you a little bit what I
want you to do is count and maybe you
want to write the numbers down but I
want you to write the numbers down and
say them out loud from five thousand
nine hundred ninety eight to six
thousand twelve so you know keep going
up one up one until you get to six
thousand twelve and it might seem like
you have to go a long way but take my
word for it you're not that far from and
then you can figure out how far you are
when you when you do the numbers so
pause now and try it yourself pause
right now and I'm well now I'm assuming
that you've paused and restarted and now
I'm going to tell you how to do it and
hopefully you figured it out but so
let's see we're gonna start at five
thousand nine hundred ninety-eight and
we're gonna keep going up until we get
to six thousand and twelve let me let me
do it in with with our colors so we
started off at 5900 this might take a
little more time if I do it with the
colors but why not five thousand nine
hundred ninety-eight so what happens
when we add one to this to five thousand
nine hundred ninety-eight
well we'll we'll just get we just add
one to the ones place and so that eight
becomes a nine right so we add one so we
get a nine there and so we what's the
number that we get we get five
and 999 99 now this is where it gets
interesting right we have five thousands
right five thousand cans 999 what
happens when we add one more well what's
one more than nine well you want to say
ten right you want to say well that that
gets me to ten and then you would have
you know you could say five thousand
nine hundred ninety ten perhaps you
could say that but remember just think
about this in terms of filling up
marbles all of a sudden we in the ones
place
we have enough marbles to to fill up a
ten can right so let's let's fill up a
new ten can so let's take all of these
marbles and put them into a ten can so
what happens we we could instead of we
could take these ten marbles and we
could put it into one ten can one ten
can so if I wanted to expand this out
how do I write this number I could write
this as five thousand and I'm gonna
focus on this a lot because it's really
interesting what's happening right into
here this is five thousand plus nine
hundred switch colors again plus ninety
right nine ten cans and then I have
another plus I have another ten can and
now I have no more ones right because I
took all of these and I put them into a
tin can
I hope I'm not confusing you so how many
ten cans do we have well we had nine now
we have one more so we have ten ten cans
so we could write this instead of five
thousand nine hundred ninety ten maybe
we could write it as and you could see
we're gonna go through this several
times okay we could rewrite this as we
took all of these that we made it into a
ten can so maybe we could write this as
five thousand nine hundred and then ten
on ten tens ten tens which is here and I
think I'm confusing you right because
that's that's the number of ten cans we
have and then zero ones left over but
once again we can't and this
I'm doing this for a reason I mean this
is I mean let me see what it this is the
thousands place hundreds place tens
place once place this is a five thousand
this is the thousands place hundreds
tens once and the reason why we keep
running into the problem is you can't
have ten as a digit in each place you
can only have a numeral between zero and
nine you can have zero one two three
four five six seven eight nine you can't
have a ten there so whenever you have a
ten you fill up essentially and you can
and so then you have one more ten can
but you can't have ten ten cans
what does ten ten cans fill up well that
fills up a hundred can right so we could
take these ten ten cans and fill up one
hundred cans so maybe we could write
this and then if we felt one hundred can
we had nine how many hundred cans we
have well we have ten hundred cans now
I'm sure I'm confusing you or this might
be obvious to you either way let's just
let's see so we could say we have five
thousand or five thousand cans we could
say we have ten hundred cans but that
doesn't make sense right that's the
hardest place and then we now have 0 10
cans it's a slightly different color and
0 1 cans so these are let me draw the
places because you can't have a
two-digit number in a place but I'm just
doing this for a reason so these are our
places we have five thousand cans ten
hundred cans zero ten cans and zero one
cans and these are all kind of the same
number although none of them are valid
right because you can't have ten in a
place you have to have a digit so what
happens if you have ten hundred cans
well we can fill out we can fill up
another thousand can right cuz ten
hundred cans is equal to a thousand can
so let's take these ten hundreds and add
one to the thousand so this could be six
thousand cans and we took all those ten
hundred so we have no longer any hundred
cans we no longer have any ten cans and
we no longer have any one cans and now
we are fine because in every place we
have a numeral between zero and I will
have some kind of weird two-digit number
within the place and as you can see the
number right after five thousand nine
hundred
nine is not five thousand nine hundred
ninety ten or five thousand nine hundred
ten zero or five 1000 these are all
bizarre numbers and I apologize it too
confusing the number right after it is
six thousand I did all of that work just
to go from five thousand nine hundred
ninety nine to six thousand and
hopefully that makes sense to you now
because it's you can't go from nine to
ten you're essentially filling up a ten
bucket but when you fill up another ten
bucket you now have ten tens so you
could actually fill up another hundred
bucket but when you fill up another
hundred bucket you now have ten hundred
buckets so you fill up another thousand
buckets and now you have six thousand
buckets and you you don't have any extra
marbles so you have exactly six thousand
marbles so that was a hard part so we
went from five thousand nine hundred
ninety eight to five thousand nine
hundred ninety nine to six thousand and
from here it's easy what's the next
number I don't even have to do place
notation here I think it's six thousand
and one 6002 six thousand and three
six thousand and four I'm going to
confuse you by going over all the way
here but it's six thousand and five six
thousand and six six thousand and seven
six thousand and eight six thousand and
nine my god six thousand ten six
thousand eleven six thousand we write
this in a bowl um tired six thousand and
twelve and we are done so that wasn't
too bad
the important things to realize is what
happens when you go from five thousand
nine hundred ninety nine to six thousand
that extra one doesn't all only fill up
a ten bucket which the ten bucket start
overflowing so you fill up a hundred
buckets so that fill but then you have
ten hundred buckets so you actually are
able to fill up a completely new
thousand bucket so you have six thousand
marbles at that point so let's do let's
do that again with a with a with another
set of numbers and now just to save time
and maybe cuz you know you're you're
smarter than me we don't need to do the
colors anymore so let's go from this
number to this number and you might want
to try it by yourself before we before I
give you the answer so pause now if you
want to but anyway so what is this
number we have
nine thousand nine hundred eight tens so
that's eighty seven 9987 what's the next
number we will just keep incrementing
there let me use a vibrant color let me
see this blue looks nice so the next
number is that's the same color well
I'll stick with it let me do a slightly
different that's nine thousand nine
hundred eighty we just increment the one
we're just adding one at a time eighty
eight nine thousand nine hundred eighty
nine and now what happens this is
interesting if we want to increase this
by one what's one more than nine well
it's ten but we can't have a tan here in
the ones place so we're essentially
adding we can take all of these here so
we're gonna have tan ones and make a new
ten right so essentially we can take we
could take add the one that becomes a
ten so we have one more ten so that
becomes 90 right what's 89 plus one it's
90 so now we have nine thousand nine
hundred ninety and now the next few were
pretty easy nine thousand nine hundred
ninety-one
nine thousand nine hundred ninety two
nine thousand nine hundred and ninety
three and I will arbitrarily switch
colors for no reason nine thousand nine
hundred ninety four nine thousand nine
hundred ninety five nine thousand nine
hundred ninety six nine thousand nine
hundred ninety seven let me go to yellow
9,998 9,999 now what happens well if I
add one more I get ten ones so I could
add another ten bucket another ten can
right but if I had another tenth can
then I'll have ten tens and I can't have
ten in the tens place so then I
essentially have another hundred right
what's 99 plus one it's a hundred but if
I have another already have nine
hundreds so if I have another hundred
I'll have ten hundreds so ten hundreds
is a thousand so I essentially when I
add one more to 999 I essentially get
another thousand so I add one to the
thousands so now I have well now now I
actually have ten thousand right ten
thousands right so you know you could
instead of having a ten in the thousands
place I actually
a new bucket I have actually now have a
one I have one ten thousand bucket so
what happens so I have you know instead
of having instead of having this be ten
in that place and then you know zero
zero zero although it look it's looking
exactly the same this is we can't have a
ten in the thousands place so what we do
is we say well no we don't have ten one
thousands we have one ten thousand so
this is a new bucket this is a bucket
this is a can size that's made out of
ten thousands we have one of them and
I'll do it in a new color we have one of
those and then we have no thousands left
over hundreds left over tens leftover or
ones left over so we have ten but the
way this is said it's not said one ten
thousands this is said this is red
actually not too different than this
it's red as ten thousand so hopefully
that doesn't confuse you and you know
more than thinking about what happens as
we fill up buckets the nine goes to ten
but you can't have ten there so you put
the one here but then that becomes to
ten then that goes to ten you keep going
oh my god my phone is ringing loudly but
let me just let me just finish this
before I answer the phone because you
are more important but the important
thing is to realize that is to see the
pattern that what happens when you add
1/2 a bunch of nines you essentially go
to the next place and you might want
experiment you know see what happens
when you when you go from the number 97
to the number 102 right you go 97 98 99
and then when you add one more you can't
have 90 10 right you can't have 90 10 so
you want to add one more here but what
happens you can't have 10 10 zero I
think I'm confusing you if you go to 100
all right this is a new place and
similarly instead of having 10 in the
thousands place you go to a new place or
the ten thousands place which is here so
this is 10 thousands that's thousands
that's hundreds that's tens that's zeros
I think this might be pretty intuitive
for you and when you kind of do all the
labels it might be a little confusing
but anyway I'll leave you there and I'll
see you in the next video