Have you ever wondered how a percent could be a decimal? Take a look at this dilemma.
Karen earned 85% on a math test. She wondered how she could show this as a decimal. Do you know?
A percent is a part of a whole. It is a ratio compared to 100.
Fractions and decimals are parts of a whole too. If this is true, then we can interchange the form that we write these quantities in. We can write a fraction as a decimal and as a percent. We can also write a percent as a decimal or a decimal as a percent and we can do the same with the fractions too.
Let’s start by writing percents as decimals and decimals as percents.
We can start by thinking about decimals. Decimal places represent powers of ten. The second decimal place is the hundredths place. The decimal .18 means eighteen-hundredths.
Exactly, and now you might be able to see how we can write percent as a decimal. They are both comparing to hundreds.
Take a look at this one.
Write 56% as a decimal.
To do this, we know that the % sign means “out of 100” we can say that decimal places represent tens and hundreds too. Two decimal places represents hundreds, just like the percent sign, %, represents hundreds.
To change a percent to a decimal, we drop the percent sign and move the decimal point two places to the left.
56% = .56
Write this down in your notebook.
Write 88% as a decimal.
To do this, we drop the percent sign and move the decimal point two places to the left.
88% = .88
Write 125% as a decimal.
Even though this percent is greater than 100, we still follow the same steps.
125% = 1.25
We can work the other way around too and write decimals as percents. Here we will move the decimal point two places to the right and add a percent sign.
Write .45 as a percent.
First, we move the decimal point two places to the right and add a percent sign.
.45 = 45%
Write .345 as a percent.
Follow the same rule here. Just move the decimal point two places to the right and add a percent sign.
.345 = 34.5%
Write this rule down in your notebook.
Write each example as a decimal or a percent.
Now let's go back to the dilemma from the beginning of the Concept.
To convert to a decimal, we first drop the percent sign.
Next, move the decimal point two places to the left.
This is our answer.
- A ratio is a comparison of two quantities that can be written in fraction form, with a colon or with the word “to”.
- Percent means out of 100. It is a quantity written with a % sign.
- A fraction is a part of a whole. A fraction is written mathematically as one value on top of another, separated by a fraction bar. It is also called a rational number .
- In common use, a decimal refers to part of a whole number. The numbers to the left of a decimal point represent whole numbers, and each number to the right of a decimal point represents a fractional part of a power of one-tenth. For instance: The decimal value 1.24 indicates 1 whole unit, 2 tenths, and 4 hundredths (commonly described as 24 hundredths).
- A proportion is an equation that shows two equivalent ratios.
Here is one for you to try on your own.
Write as a percent.
When converting a decimal to a percent, we move the decimal point two places to the right. This represents the hundredths that are shown with a percent sign.
Now we add a percent sign.
Our answer is .
Write the following percents as decimals.
Write the following decimals as percents.