# Percentages, Fractions, and Decimal Values

## Percentages are defined as a fraction or portion of a whole. Generally percentages deal with an amount out of one hundred but can be used in sales, economics, and science. If you've walked into any store you're sure to find something marked a certain percent off. Fractions are not whole numbers with a numerator over a denominator. Usually the numerator and denominator are expressed as integers. There are four types of fractions: simple fractions, complex fractions, mixed fractions, and improper fractions. Decimals are also not integers. They are expressed often like 0.34 and are often rounded off since some go for too long. Both decimals and fractions are also used to convert to percentages.

###### Asked in Math and Arithmetic, Chemistry, Statistics, Percentages, Fractions, and Decimal Values

### What is the percent error formula?

Percent Error is the difference between the true value and the
estimate divided by the true value and the result is multiplied by
100 to make it a percentage. The percent error obviously can be
positive or negative; however, some prefer taking the absolute
value of the difference.
The formula is the absolute value of the experimental value
(minus) the theoretical value divided by theoretical value times
100.
% error = (|Your Result - Accepted Value| / Accepted Value) x
100

###### Asked in Math and Arithmetic, Mathematical Finance, Percentages, Fractions, and Decimal Values

### What is 20 percent of twelve thousand one hundred dollars?

I never saw much point in giving the answer to a mathematical
question if the person didn't explain how to get to that
answer.
With calculators today many mathematical equations are easy to
figure, but I am a strong believer in the person understanding the
formula and how it works, not just typing numbers into a calculator
and magically getting an answer.
The question is what is 20% of $12,100. First we must change the
percentage to a decimal, this is easily done by moving the decimal
place to spaces to the left (the % represents the decimal).
Therefore it gives us .20
Then simply multiply $12,100 x .20
12,100 x .20 = 2,420
Since we know we are dealing in dollars the answer is $2,420

###### Asked in Math and Arithmetic, Percentages, Fractions, and Decimal Values

### What is 25 percent of 80.00?

The easiest and simplest way to calculate a percentage of any
number is to remember that 10% of any number, is the number itself
with the decimal point one place to the left.
I.e 10% of 1478 is 147.8 (The decimal one place to the
left)
10% of 100,000,000 is 10,000,000.
That means that 10% of 80.00 is 8.000 (keeping the insignificant
digits). So 20% would be $16.00. But we need 5 percent more, so
we just split our 10% in half. Half of 8 is 4. So 25% of 80.00 is
16 + 4 which is 20.

###### Asked in Algebra, Numbers , Percentages, Fractions, and Decimal Values

### What is a decimal of 140 percent?

The percent sign % can be defined as "divide by 100".
So the decimal of 140% would be 140/100 or 1.4
So if you wanted to know what 140% of any number was you could
multiply by
1.4 i.e. 140% of 50 is 50 x 1.4 = 70, or since multiplication is
distributive you
could also do this (140 x 50)/100 which will also give you
70
1.4

###### Asked in Math and Arithmetic, Percentages, Fractions, and Decimal Values

### How do you do recurring decimals to a percentage?

Multiplying decimals by 100 will convert them to
percentages.
If you wish to remove the recurring decimal, convert it to a
fraction by putting the recurring digit(s) as the numerator over a
denominator of the same number of 9s and reducing the fraction to
its lowest terms.
Examples
0.333333333...
To a percentage: 0.333333333... x 100 = 33.3333333...%
0.3333333... as a fraction: repeating digit is 3 so put as the
numerator over a denominator of one 9 to give the fraction 3/9 =
1/3
So 0.333333333... = 33 1/3 %
0.1428571428...
To a percentage: 0.1428571428... x 100 = 14.28571428...%
0.28571428... as a fraction: repeating digits are 285714 of
which there are six, so put as numerator over a denominator of six
9s to give the fraction 285714/999999 = 2/7
So 0.1428571428... = 14 2/7 %

###### Asked in Math and Arithmetic, Percentages, Fractions, and Decimal Values

### How many ppm in one percent?

10,000 ppm
Solution Method:
1. A ppm = 1/1,000,000 = 0.000001
2. What you want to know is: how many ppm would = 1%
3. p * .000001 = .01
4. p = .01 / .000001
5. p = 10,000
You could also do it this way:
1. 1% of 1,000,000 = ppm = 10,000 ppm (but that method lacks a
clear path to understanding).
===
previous answer's method:
1%=1/100=1000000/100=10000ppm.

###### Asked in Math and Arithmetic, Percentages, Fractions, and Decimal Values

### How do you increase 80 by 40 percent?

Method 1:
80 * .4 + 80 = 32 + 80 = 112
Method 2:
1. Add 100% to 40% = 140%
2. Convert 140% to decimal form: 140%/100 = 1.4
3. Multiple 1.4 * 80 = 112 <--- this is your answer.
Note: The reason you add 100% to the 40% is because the phrase
"increase 80" means you have to add 100% of 80 (which is 80 *
(100%/100) = 80 * 1 = 80) to the increasing percentage (80 * 40% =
80 * (40%/100) = 80 * .4 = 32) to get your final answer (80 + 32 =
112).
It looks like this in summary form:
80 * 100% = 80 * (100%/100) = 80 * 1 = 80
80 * 40% = 80 * ( 40%/100) = 80 * .4 = 32
80 + 32 = 112
You should be able to easily see that you can add 100% + 40% to
get 140%, which converts to the decimal number 1.4
1.4 * 80 = your answer (i.e. 112).
==============
Previous explanation:
Right so you take 80, divide it by 10 (100 if you wanna stay
with the full shabang) then multiply it by 4 (40 if you have
already divided by 100) and the answer will be 32. add this number
to 80.
The answer is 112