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Current time:0:00Total duration:4:24

CCSS Math: 4.MD.A.1

So I have two conversion
scenarios right over here. I want to convert 3
kilograms into milligrams. And I want to convert
4 tons into ounces. So this is clearly
in the metric system. And this right over here is
in the US customary system. So I encourage you
pause this video and try to do these
conversions on your own. Well, to think about
this one, we just have to think about what
these prefixes mean. So I could rewrite
this is 3 kilograms, and we're going to convert it
into some amount of milligrams. And we've already seen that the
prefix "kilo," this literally means 1,000. And the prefix "milli," means 1
over 1,000 or 1,000 of a gram. So let's just convert
to grams first. Let's go from
kilograms to grams. And then we can go from
grams to milligrams. So we could say
that 3 kilograms is going to be equal to
3 times 1,000 grams. So this is equal to 3,000. This is literally 3,000 grams. That's one way to
interpret "kilo," so this gets us to 3,000 grams. Now, how to go from the
grams to the milligrams? Well, we already
said right over here that 1 milligram--
Let me write it here, 1 milligram is equal to 1
over 1,000 or 1,000 of a gram. But another way of thinking
about this statement is that 1 gram is equal
to 1,000 milligrams. So if we keep this in
mind, we have 3,000 grams. Each of those are going to
be equal to 1,000 milligrams. So this is equal to 3,000 grams. Each of those are equivalent
to 1,000 milligrams, so times 1,000. And this is going to give
us the number of milligrams. And what is this going to be? 1,000 thousands is a million,
so 3,000 thousands is 3 million. This is going to get us
3 million milligrams. Another way to think
about this multiplication, I've got 3 zeroes,
here 3 zeroes here, so my final product
should-- so 3 times 1 is 3, and then I should follow
that with the 6 zeroes so I get 3 million milligrams. Now let's do the
same thing over here. Let's convert this US customary
ton right over here to ounces. What we'll do first is we'll go
to pounds, and then from pounds we can go to ounces. And we know that 1 ton
is equal to 2,000 pounds. So 4 tons are going to be
equal to, well each of those are going to be 2,000 pounds. So it's going to be
4 times 2,000 pounds. Which is equal to 8,000 pounds. Make sure I have
some space here. Now how many ounces are
in each of those pounds? Well, we know that
1 pound, we know that 1 pound is
equal to 16 ounces. So 8,000 pounds,
so this over here-- so let me write
this, 8,000 pounds. If each of those 8,000 have
16 ounces, or equivalent to 16 ounces, this is going to
be 8,000 times 16 ounces. So what is 8,000 times 16? So this is going to be 8
times 16 is 80 plus 48 is 128. But we want to do 8,000 times,
so it's going to be 128,000. So 4 tons are a lot of ounces.