Video Transcript
In this video, we will look at how we
convert percentages to decimals. We will begin by recalling some basic
facts about percentages and decimals. The word percent means out of 100. This means that 38 percent can be written
as the fraction 38 over or out of 100. As the line in a fraction means divide,
this is the same as 38 divided by 100. Dividing by 100 moves all our digits two
places to the right. So, 38 percent is the same as 0.38.
We can therefore say that in order to
convert from a percentage to a decimal, we divide by 100. This means that the opposite must also be
true, that to convert from a decimal to a percentage, we multiply by 100.
In this video, we will focus on the first
one of these, converting from a percentage to a decimal. We will now look at some questions where
this is the case.
Express 44 percent as a decimal.
As the word percent means out of 100,
we can write 44 percent as a fraction, 44 over or out of 100. The line in a fraction means divide, so
we can write this as a decimal by dividing 44 by 100. This is equal to 0.44 as all the digits
move two places to the right. 44 percent expressed as a decimal is
0.44. To convert any percentage into a
decimal, we need to divide by 100.
We will now look at some questions in a
real-life context.
According to a recent survey, 21
percent of people prefer apples over oranges. Express 21 percent as a decimal.
In order to convert from percentages to
decimals, we divide by 100 as the word percent means out of 100. When dividing by 100, all of our digits
move two places to the right. 21 divided by 100 is therefore equal to
0.21. This means that 21 percent expressed as
a decimal is 0.21.
If the sales tax in a town is 2.34
percent, express the percentage as a decimal.
We know that the word percent means out
of 100. This means that in order to convert any
percentage into a decimal, we need to divide by 100. In this question, we need to divide
2.34 by 100. As all of our digits move two places to
the right, this is equal to 0.0234. The sales tax, 2.34 percent, expressed
as a decimal is 0.0234.
Our last couple of questions involve
carrying out a calculation before converting from a percentage to a decimal.
Mason did 32 percent of the yard work
while Benjamin did 14 percent. Which decimal represents the amount of
work they completed together?
We’re told in the question that Mason
did 32 percent of the work. Benjamin did 14 percent. To calculate the percentage they
completed together, we need to add 32 percent and 14 percent. This is equal to 46 percent. Mason and Benjamin together completed
46 percent of the yard work.
We’re asked in this question to
represent this percentage as a decimal. To convert from a percentage to a
decimal, we divide by 100. 46 divided by 100 is 0.46. As 46 percent is the same as the
decimal 0.46, then this represents the amount of work that Mason and Benjamin completed
together.
Our final question involves a mixture of
fractions and percentages.
In a school, 38 and one-fifth percent
of students signed up to visit a local zoo. Express this percent as a decimal.
There are lots of ways of approaching
this problem. One way would be to split 38 and
one-fifth percent into 38 percent and one-fifth of a percent. Let’s consider 38 percent first. As the word percent means out of 100,
we know that 38 percent is equal to 38 over 100. This is the same as 38 divided by 100,
which equals 0.38. This means that 38 percent is the same
as the decimal 0.38.
Let’s now consider one-fifth of a
percent. The fraction one-fifth is the same as
two-tenths. This is because we have multiplied the
numerator and denominator by two. Two-tenths is the same as 0.2, as two
divided by 10 is 0.2. We can therefore say that one-fifth of
a percent is the same as 0.2 percent.
To convert from percentages to
decimals, we divide by 100. 0.2 divided by 100 is 0.002 as all the
digits move two places to the right. One-fifth of a percent written as a
decimal is 0.002. Adding this to 0.38 gives us 0.382. 38 and a fifth percent written as a
decimal is 0.382.
We will now summarize the key points from
this video. The first thing we established was the
word percent means out of 100. This means that 67 percent can be written
as the fraction 67 over or out of 100. Dividing 67 by 100 gives us 0.67. So, 67 percent expressed as a decimal is
0.67. This meant that in order to convert from
a percentage to a decimal, we need to divide by 100.
As multiplying is the opposite or inverse
of dividing, to convert from a decimal to a percentage, we multiply by 100. This means that four percent is equal to
0.04, 125 percent is equal to 1.25, and 14.8 percent is equal to 0.148. When dividing by 100, all of our digits
move two places to the right. By dividing and multiplying by 100, we
can convert from a percentage to a decimal and vice versa.
