How to explain 2 Digit Multiplication
2-Digit by 2-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 two digit numbers by two digit
numbers
and we have two examples that we're
going to go through together
in order to get this down so let's find
each product here
and remember product means the answer to
a multiplication problem
so for number one we have 39 times 24
and the first thing we need to do is set
this problem up
and we can do that by writing 39
times 24 when setting these problems up
just make sure that your places are
lined up meaning the 9 and 4
are lined up because they are both in
the ones place
the three and two are lined up because
they are both in the tens place
so the process that we're going to go
through essentially what we're going to
do we're going to do 4 times 39
and then 20 times 39 now i said
20 times 39 because the 2 in 24
has a value of 20. so let's go through
this process
and the first thing we're going to do is
4 times
9 which gives us 36.
now we carry our 3 to the tens place
there
next we do 4 times 30 and i say 4 times
30 because the 3 in 39
has a value of 30 but we can just think
of it as
the simple digits of uh four times three
here
so four times three is twelve plus that
three that we carried
is fifteen now i'm just going to drop my
one here because i don't have any more
places to carry that one to
so i am done doing four times 39 so i
can cross off the four because i'm done
with that
and i'm done with this three here
crossing things off when you're done
with it
helps you so you don't get confused with
any other numbers that we carry
later on in the problem now this next
step is very important
we need to put a zero here for when we
do
20 times 39 and we put that zero there
because the 2 in 24 has a value
of 20 so that 0 represents that
now we go through our process 2 times 9
is 18. so we put our 8 and carry
our 1. see why we crossed out that 3
earlier
so we don't get it confused with any
other numbers we carry
then we do 2 times 3 which is 6
plus that 1 is 7.
so we have four times 39 is 156
and 20 times 39 is 780.
now we add these two answers together to
get our final answer or product
so six plus zero is six five
plus eight is thirteen one plus one is
two plus that seven is nine
so we get a final answer of 936
so on to number two where we have 68
times 57
so let's line our problem up
and now we're ready to solve so we need
to do 7 times
68 and 50 times 68
7 times 8 is 56 carry our 5
7 times 6 is 42
plus 5 is 47
so we get 476. we are done with this 5
here
and we are done with this 7. now that
we're moving over to the 5
of 57 that 5 has a value of 50
so we need a 0 here
before we can continue on now we do
5 times 8 which is 40.
so we have a 0 carry the 4.
5 times 6 is 30 plus that 4 is 34 so i
put my 4
and there are no more places to carry
that 3
to so we can drop it there
and now we can add these partial
products those are called partial
products because they're
they are part of our final product so
add them together
six plus zero is six
seven plus zero is seven four plus four
is 8 and then we have our 3 there
so 3 876
is our final product there so there you
have it there's how you multiply
two digit numbers by two digit numbers i
hope that helped
thanks so much for watching until next
time
peace
