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Current time:0:00Total duration:3:15

CCSS Math: 4.NBT.B.6

In this video,
I'll introduce you to a new way of
computing division, especially for larger numbers. And then we'll think a little
bit about why it works. So we're going to try to
compute what 96 divided by 4 is. And I'm going to write it
a little bit differently. I'm going to write 96
divided by-- so I'm going to write this
strange-looking symbol right over here, this
thing that covers the 96. But you could view this
as 96 divided by 4. And I'll show you in a second
why we write it this way. This is actually a very useful
way of actually computing it. So the first thing we'll
do is we'll say, well, how many times does 4 go into 9? Well, we know that 4 times 2 is
equal to 8 and that 4 times 3 is equal to 12. So 3 would be too much. We would go above 9. So we want to be below 9 but
not have too much left over. We want the largest
number that gets us into 9 without going over 9. So we'll say it goes two times. 4 goes into 9 two times. And then we say,
what's 2 times 4? Well, 2 times 4 is 8. 4 times 2 is 8. Or 2 times 4 is 8. And now, we subtract. We subtract the 8 from the 9. And we get 1. And now we bring down the
next digit, which is the 6. And then we ask ourselves,
well, how many times does 4 go into 16? Well, in this case, we know
that 4 goes into 16 exactly four times. 4 times 4 is 16. So we say 4 goes
into 16 four times. Then we multiply
4 times 4 is 16. We subtract. And 16 minus 16, we have
absolutely nothing left over. And there we have our answer. I know it seems kind of
magical at this point. But in a few
seconds, we're going to think about why
this actually worked. We got that 96 divided
by 4 is equal to-- I want to do that in a
different color-- 24. Now, what I want you to do
right now is pause this video and think about why
did this actually work. How did we magically get
the right answer here? And you can verify this. Multiply 4 times 24,
and you will get 96. Well, I'm assuming
you gave a go at it. And the important
thing always is to keep track of
the place value. And it really tells
you what's going on when we do this process. When we looked at this
9 right over here, this 9 is in the tens place. This is actually
representing 90. It represents 9 tens. So we're saying,
well, how many times does 4 go into 90 if we're
thinking about multiples of 10? Well, it goes 20 times. 4 times 20 is 80. And so we said, well,
4 times 20 is 80. But we still have 16 left over. You do 96 minus 80. You have 16 left over
to divide 4 into. And then 4 goes
into 16 four times. So really, a lot of this
is just saying, well, we first figured out that
we could go 20 times. And then we said, well,
that doesn't get us all the way to 96. We have to go
another four times. Hopefully, that helps.