- Topics At a Glance
- Different Types of Numbers
- Natural Numbers
- Whole Numbers
- Integers and Negative Numbers
- Integers and Absolute Value
- Rational Numbers
- Irrational Numbers
- Real Numbers and Imaginary Numbers
- Different Ways to Represent Numbers
- Fractions
- Equivalent Fractions
- Mixed Numbers
- Reducing Fractions
- Comparing Fractions
- Least Common Denominator
- Addition and Subtraction of Fractions
- Multiplication of Fractions
- Equivalent Fractions and Multiplication by 1
- Multiplication by Clever Form of 1
- Multiplicative Inverses
- Division of Fractions
- Multiplication and Division with Mixed Numbers
- Decimals
- Converting Fractions into Decimals
- Converting Decimals into Fractions
- Comparing Decimals
- Adding and Subtracting Decimals
- Multiplication and Division by Powers of 10
- Multiplying Decimals
- Dividing Decimals
- Infinite Decimals
**Percents**- Portion of the Whole
- Things to Do with Real Numbers
- Addition and Subtraction of Real Numbers
- Properties of Addition
- Subtraction
- Multiplication
- Division
- Long Division Remainder
- Exponents and Powers - Whole Numbers
- Properties of Exponents
- Prime Factorization
- Order of Operations
- Even and Odd Numbers
- Infinity
- Sequences
- is Irrational
- Counting Rational Numbers
- Counting Real Numbers?
- Counting Irrational Numbers
- In the Real World
- Decimals in Use
- How to Solve a Math Problem
- I Like Abstract Things: Summary

A **percent** is an abbreviation for a fraction where the denominator is 100. "%" means "over 100." So that 64% you got on your history pop quiz last week? Yeah - that wasn't actually out of 70, sorry to say. You might want to hold off on the bragging.

Samples:

Abbreviate 3/100 - 3%

Abbreviate 42/100 - 42%

Abbreviate 200/100 - 200%

Notice that each of these fractions with denominator 100 can also be written as a decimal, so

3% = 3/100 = 0.03

42% = 42/100 = 0.42

200% = 200/100 = 2

To get from a decimal to a percent, we move the decimal point two places to the right (because there are two zeros in 100) and add a percent sign. Where did a percent sign come from, you ask? Check out what happens when we take a percent sign, shake it up a bit and rearrange the parts:

% ... ... ... ...

Hey, look at that! There's a "100" hiding in there!

When doing arithmetic with percents, it's usually easiest to turn them back into fractions or decimals first. Percents aren't the easiest things to work with, but they sure are nice for labeling milk.

To get from a percent to a decimal, move the decimal point two places to the left and erase the percent sign. Or, if your eraser doesn't work on your computer monitor, hit the "delete" key.

Remember that when it comes to fractions, "of" means "multiply." Since percents are abbreviations for fractions, this is also true for percents. It's like we have our own secret language. Hey - let's also have "sundial" stand for "banana peanut butter sandwich." Man, we could go for a sundial right now. *Wink*.

Example 1

Express the decimal as a percent. 0.034 |

Example 2

Express the decimal as a percent. 7.2 |

Example 3

Express the decimal as a percent. 0.5 |

Example 4

Express the percent as a decimal. 5.4% |

Example 5

Express the percent as a decimal. 0.03% |

Example 6

Express the percent as a decimal. 700% |

Example 7

Write "40% of 50" as an equation. |

Exercise 1

Express the decimal as a percent.

0.37

Exercise 2

Express the decimal as a percent.

4.5

Exercise 3

Express the decimal as a percent.

0.003

Exercise 4

Express the percent as a decimal.

4%

Exercise 5

Express the percent as a decimal.

200%

Exercise 6

Express the percent as a decimal.

0.03%

Exercise 7

Evaluate.

50% of 4.5

Exercise 8

Evaluate.

20% of 100

Exercise 9

Evaluate.

3% of 90