Some Helpful Tools
Math: Percents , Fractions, and Decimals- Tutorial
A percent is a part of a whole that has been divided into 100 parts. Percent means "per hundred". The symbol for percent is %.
25% 50% 75% 100%
How to Use Percentages
Interchanging Percents and Fractions
Now subtract the discount price from the original price to find the new cost of the video game.
Example 2: Let's say that the discount is 40%. What is the new price of the video game?
As you can see, the bigger the discount, the lower the final price.
Examples: Change the following percents to fractions.
5% 25% 65%
Change a percent to a fraction by placing the percent amount over 100 and dividing.
Reduce to lowest terms.
Example :
Another way would be just to divide the numerator by the denominator.
Interchanging Fractions and Decimals
Example 1:
A fraction can be changed to a decimal by dividing the numerator by the denominator.
A decimal can be changed to a fraction by placing the decimal over 100.
Since 5 is a factor of both 45 and 100, divide the numerator and the denominator
by 5 to reduce to lowest terms.
Interchanging Percents and Decimals
Example 2:
Example 1:
A percent can be changed to a decimal by multiplying the percent by .01.
35%
35% x .01 = .35
Example 2:
7%
7% x .01 = .07
Example 3:
A percent can also be changed to a decimal by placing the percent over 100 and dividing.
A decimal can be changed to a percent by diving by .01
Proportions
If you are solving a problem where part of the problem is missing, for example, the part, the whole, or the percent part, you could label the missing value with the letter (N) and set up a proportion as shown below.
Example 1: Find 25% of 250.
Hint: Since we know that the whole amount is 250, place the percent over 100 and the N over the whole.
Now cross multiply to solve for N.
Example 2: 30 is 175% of what number?
The answer is 25% of 250 is 62.5.
Hint: Since we are looking for the whole amount, place the percent over 100 and the
30 over N.
Now cross multiply to solve for N.
The answer is 30 is 175% of 17.1.
Notice that 30 is larger than 17.1. This is because 175% is larger than 100%.
This section will cover the fundamentals of interchanging percents, fractions, and decimals.
Example 1: Suppose you were shopping for a video game, and you found a 20% discount on all used games.
The original price of the video game is $17.99.
To find out how much the video game will cost with the discount, multiply the percent amount times the original price and divide by 100.
