Percentag
BY:
NOOR
Objective
At the end of class students will be able to:
• Meaning of percentage
• Formula of percentage
• How to calculate percentage
• Conversion of percentage to fraction
• Conversion of percentage to decimals
• Conversation of fraction to percentage
• Conversation of decimals to percentage
Meaning of Percentage
A percent refers to a number of parts of something, relative to the whole or
100 parts, “parts per hundred.”
Is a fraction. The denominator is 100; the numerator is the number before the %
symbol.
E.g., 5% = 5/100.
Cont..
Is a ratio: The numerator and denominator are separated by a colon.
For example, 5% = 5:100.
Is a decimal: The numerator is taken to the hundredth part.
For example, 5% = 0.05.
Is written with the symbol %, which means 100.
Formula of % and How to calculate %
• The percentage can be found by dividing the value by the total value
and then multiplying the result by 100. The formula used to calculate
the percentage is: (value/total value)×100%.
• 888/1100*100 = 80.73%
Conversion of percentage to fraction
• To change a percent to a fraction: drop the % symbol, divide the number (new
numerator) by 100 (denominator), reduce, and change to a mixed number, if necessary.
• Change 20% to a fraction
Drop the % symbol: 20% now becomes 20.
This number (20) now becomes the fraction’s new numerator.
Place this new numerator (20) over 100 (the denominator will always be
100).
20/100 =
20/100 Reduce the fraction to lowest terms = 1/5
Practice
• 15%
• 20%
• 1/3 %
• 60%
• 75%
• ½%
Conversation of fraction to percentage
• To change a fraction to a percent: multiply the fraction by 100 (change any mixed
number to an improper fraction before multiplying by 100), reduce, and add the %
symbol.
•½
• ½ *100 = 100/2 = 50 %
Conversation of fraction to percentage
• 1/5
•½
• 2/5
•¼
•4
Conversion of percentage to decimals
• To change a percent to a decimal: drop the % symbol (when you drop the % symbol
from the whole number, a decimal point takes the place of the symbol), divide the
remaining number by 100 by moving the decimal point two places to the left, and
add zeros if necessary
• 68%
• Decimal replaces the %. 68.0
• 68.0 = move the decimal 0.68.
Practice
• 15%
• 25%
• 59%
• 70%
Conversation of decimals to percentage
• To change a decimal to a percent: multiply the decimal by 100 and by moving the
decimal point two places to the right, and add the % symbol and zeros if needed;
• 0.50
• 0.50 * 100 = 50%
Practice
Convert in to percentage
• 3.19
• 1.61
• 0.25
• 0.60
Percentage one Number is of
another Number
• To determine what percentage one number is of another number: make a fraction using
the number following “what percent of” as the denominator, use the remaining
number as the numerator, change the fraction to a decimal, and then change the
decimal to a percent.
Cont.…
• What percent of 40 is 10?
• Convert to fraction 10/40 = 1/4
• Change to decimal ¼ = 0.25
• Change to a percent 0.25 = 25 %
• So, the percent of 40of 10 is 25%
Practice
• What percent of 4 is 1/2?
• What percent of 25 is 5?
• What percent of 180 is 60?
• What percent of 90 is 15?
Any Questions?
‘The greatest discovery of all time is
that a person can change his future by
merely changing his attitude’
-Oprah Winfrey.
Thanks
