How to do 3 Digit Multiplication
3-Digit by 3-Digit Multiplication | Math with Mr. J
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[Music]
welcome to math with mr j
[Music]
in this video i'm going to cover how to
multiply three digit numbers by three
digit numbers
so let's get into our two examples here
and find the product of each
and when i say product that means the
answer to a multiplication problem
so for number one we have 819 times 237
so the first thing we need to do is line
this problem up
so we have 819 times
237 make sure you line up all your
places
so the nine and seven are lined up
because they are in the ones place
the one and three because they are in
the tens and then the eight
and 2 because they are in the hundreds
now we're ready to multiply so what
we're going to do we're going to do
7 times 819 30 times 819
and then 200 times 819
add all of those up and that will give
us our final answer
and i said 30 because that 3 in 237
is in the tens place so it has a value
of 30.
and i said 200 because that 2 in 237 has
a value of 200
because it's in the hundreds place so
let's start
and we start by doing 7 times 9
which is 63 so we put our 3 and carry
the 6. now we have 7 times
10 but we can just think of it as 7
times 1
and look at these as the basic digits
now i said 10
because that 1 is in the tens place so
it has a value of 10.
but let's just think of it as the digits
themselves like i said so seven times
one
is seven plus six is thirteen
so we put our three and carry the one
now we have seven times eight hundred
but we can just think of it as seven
times eight
which is 56 plus that one is 57
so we put our seven and we don't have
any more digits
to carry over to so we drop our five
and we get an answer of five thousand
seven hundred thirty three
we are done with the seven here the six
and the one
i like to cross things off as we go uh
when we are done with them that way we
don't get confused with any other
numbers that are carried
later in the problem so now we move to
the 30
that has a value of or i'm sorry we move
to the 3 that has a value of 30.
so we put a 0 here for our next step
and that represents that 30. it helps us
represent the 30
rather than just saying it is a 3.
so now we do 3 times 9 which is 27
carry our 2. 3 times one
is three plus two is five and then three
times eight
is twenty-four so we are done with this
three
and then the two so we moved the two
in 237 which has a value of 200 it's in
the hundreds place
so we need two zeros for this next
number again that's to represent the
200 so now we do 2 times nine is
eighteen
carry the one two times
one is two plus that one is three
and then we have two times eight which
is sixteen
so now we can add all of these up these
are our partial products so they are
part of our final product or
answer there add them up and we get our
final answer
so three plus uh a couple of zeros there
is three three plus seven is
ten carry our one one plus seven is
eight
plus five is thirteen plus eight is
twenty one two plus five is seven
plus four is eleven plus three is
fourteen
one plus two is three plus six is nine
and then we end with a one here and we
get a final answer of one hundred ninety
four thousand
one hundred three so on to number two
and we can line up our problem
338 times 193 so let's go through our
steps and
we will go a little quicker as we work
through number two
three times eight is twenty-four
three times three is nine plus two is
eleven
3 times 3 is 9 plus 1
is 10 so we are done done
and done we move to the 9 which has a
value of 90
so we need a 0 here nine times eight
is seventy-two
nine times three is twenty-seven plus
seven is thirty-four
nine times three is twenty-seven plus 3
is 30. so we are done here done here
and done here now we have 100 times 338
so that 1 has a value of 100 so we need
two zeros now
one times eight is eight one times three
is three and one times three is three
so we have our three partial products
and we are ready to add them up
in order to get our final answer so four
plus zero
plus zero is four one plus two plus zero
is three zero plus four is four
plus eight is twelve one plus one is two
plus three is five and then we end with
three plus three which is
six so we get sixty five thousand
two hundred thirty four so there you
have it there's how you multiply
three digit numbers by three digit
numbers i hope that helped thanks so
much for watching
until next time peace
