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## Lesson 14: Solving percentage problems

## Video transcript

Let's give ourselves
a little bit of practice with percentages. So let's ask ourselves, what
percent of-- I don't know, let's say what
percent of 16 is 4? And I encourage you
to pause this video and to try it out yourself. So when you're saying
what percent of 16 is 4, percent is another way of
saying, what fraction of 16 is 4? And we just need to write
it as a percent, as per 100. So if you said what fraction
of 16 is 4, you would say, well, look, this is
the same thing as 4/16, which is the same thing as 1/4. But this is saying what
fraction 4 is of 16. You'd say, well, 4 is 1/4 of 16. But that still doesn't
answer our question. What percent? So in order to write
this as a percent, we literally have to write
it as something over 100. Percent literally
means "per cent." The word "cent" you know
from cents and century. It relates to the number 100. So it's per 100. So you could say,
well, this is going to be equal to question mark
over 100, the part of 100. And there's a bunch of ways
that you could think about this. You could say, well, look,
if in the denominator to go from 4 to 100, I
have to multiply by 25. In the numerator
to go from-- I need to also multiply by 25 in order
to have an equivalent fraction. So I'm also going
to multiply by 25. So 1/4 is the same
thing as 25/100. And another way of saying 25/100
is this is 25 per 100, or 25%. So this is equal to 25%. Now, there's a
couple of other ways you could have thought about it. You could have said
well, 4/16, this is literally 4 divided by 16. Well, let me just
do the division and convert to a
decimal, which is very easy to convert
to a percentage. So let's try to actually do
this division right over here. So we're going to
literally divide 4 by 16. Now, 16 goes into 4 zero times. 0 times 16 is 0. You subtract, and you get a 4. And we're not satisfied
just having this remainder. We want to keep adding zeroes to
get a decimal answer right over here. So let's put a decimal
right over here. We're going into
the tenths place. And let's throw some
zeroes right over here. The decimal makes sure
we keep track of the fact that we are now in the
tenths, and in the hundredths, and in the thousandths place
if we have to go that far. But let's bring another 0 down. 16 goes into 40 two times. 2 times 16 is 32. If you subtract, you get 8. And you could bring
down another 0. And we have 16 goes into 80. Let's see, 16 goes
into 80 five times. 5 times 16 is 80. You subtract, you have no
remainder, and you're done. 4/16 is the same thing as 0.25. Now, 0.25 is the same thing
as twenty-five hundredths. Or, this is the same
thing as 25/100, which is the same thing as 25%.