hey guys it's Kaeleigh in this lesson we're going to learn how to multiply
with decimals are you ready let's get started
so to start off here we're going to use a number that's a decimal and a number
that's a whole number to multiply together so the first thing we do is
we're gonna line them up to the right side so I'm gonna say 1.5 times 2 equals
you notice I lined up my numbers to the right side so not by place value now
we're going to ignore our decimal point for the time being we're just going to
pretend like we're multiplying as whole numbers so 2 times 5 that's 10 I carry
my 1/2 times 1 that's 2 I add my carry that that's 3 so now I've done my
multiplication as if this is just whole numbers like 15 times 2 now what I do is
I go back to my decimal point and I count how many total decimal points
there are in this problem so in this one it's just 1 so I go into my answer I go
to the end and I move my decimal point the same amount 1 and I put it there
so I can say 1.5 times 2 is equal to 3 point 0 which is equal to 3 is right
there all right now let's try one where we have both numbers as decimals so in
this one you'll see we have two decimals that we are multiplying together 1.6
times 1.9 so let's write them out I have one point six times one point nine
equals so remember the first thing I do is I'm going to ignore my decimal points
for the time being and I'm just gonna multiply as if these are two whole
numbers so I'm gonna start over here with my 9 9 times 6 is 54 so I put a 4
down there carry my 5 9 times 1 is 9 plus 5 is 14
add my 0 here remember because I'm moving over to my tens place now for
pretending like our decimals right there I'm gonna say 1 times 6 that's 6 and 1
times 1 one number I add my products together 4 plus 0 is 4 6 plus 4 is 10 I
carry my 1 1 2 & 3 so now I have my whole number as if I was multiplying 2
whole numbers but now what I do is I add at my total decimal places for the
entire problem so here I have 1 and here I have another 1 so 1 + 1 that's 2
decimal places and I need to move so now I go down to my answer and I'm moving my
decimal place two places so there's 1 2 so my total answer is 3.04 that one
right there nice work let's do one more together to really secure what we've
learned all right so the final one we're going to do together it says one point
one times two point three so let's write it out one point one times two point
three is equal to remember for the first part here I'm going to pretend as if I
just have whole numbers I'm going to multiply as I normally would so 3 times
1 is 3 3 times 1 again is 3 I'm moving over so I put my 0 here 2 times 1 is 2 2
times 1 is 2 I add my products together 3 plus 0 is 3
3 plus 2 is 5 and I bring my 2 down there now I add at my decimal points of
our decimal places so I have 1 2 so I need to move to total decimal places
over in my answer here so I put my decimal place at the end and now I move
it over two places one two decimal point so my total answer is 2
point five three looks like that one right there
nice work so now go ahead and do the online quizzes and play the game to
practice what you've learned about multiplying decimals have fun and
remember to be clever