Converting Fractions to Decimals Two methods: 1. Building a fraction to a base ten number 2. Dividing numerator by denominator

Building up the fraction to a base ten number: .5 x .20 1.75

8/3 : Repeating Decimal = Put a bar over the first number(s) that repeats And drop the rest.

Mixed Fraction to a Mixed Decimal Whole numbers are to the left of the fraction And to the left of the decimal numbers; Convert fractional part to decimal by Dividing

Section Understanding Percent

Percent, %, means per hundred. The percent number is that number compared to a total of 100. Example: For every $100 invested, you received $6 in return; the interest rate is 6 %

What is the percentage for the following: 386/100 1/100 .07/100 386% 1 % .07%

Write as a decimal 38% 6% 47% 375% .38 .06 .47 3.75

What are the rules to change % to a decimal? Ex: 82% Drop the % symbol 82 Perform the operation the symbol represents - Divide by 100 - move decimal 2 places .82 What is the clue word? Per - per hundred means divide by 100

Writing a Decimal as a Percent Move the decimal point two places to the right – (multiply by 100) 0.47 (100%) = 47 Add the % symbol at the end of the number 47%

Which way to move decimal? Remember the alphabet D before P L before R 52% D   P L   R .52 .005 D  P L   R .5%

For every 100 total items, there is 47. Remember - 47% is 47 out of every 100. A ratio is a comparison BUT You may not have 47 items. For every 100 total items, there is 47. If there were 10 total items, you would have 4.7 items

Changing Between Percents, Decimals, and Fractions Percent to fraction Drop the symbol Write the percent number over 100 reduce 75% 75 75/100 3/4

Example: 225% Rewrite % symbol as 1/100 225 1 __1_ x = 225 100 100 = 225 100 100 Simplify (reduce fraction) 2 25/100 = 2 1/4

% Example Change to improper fraction Change symbol to fraction % Reduce

¼ ¾ ½ Memorize the following equivalents 25% 50% 75% 33 1/3% 1/3 66 2/3% 10% ¼ ½ ¾ 1/3 2/3 1/10

Fraction to Percent Can you easily change the denominator to equal 100?

If denominator cannot be changed easily to 100, find decimal number first. 16.67% Rounded to the nearest Hundredth of a percent

Another method – fraction to percent: Write a proportion Cross multiply 7*100 = 8 n 700 = 8n Divide by 8 8 8 n = 87.5%

Changing a fraction to a percent containing a fraction: Stop the division after two steps

Solving Percent Problems Using an equation Translating a Percent Problem into an Equation

What is 5% of 19.00? N = .05 x 19.00 N = .95 35% of what is 60? .35 x N = 60 N = 60 / .35 N = 1714.2 Find 0.6% of 400 N = .006 x 400 N = 3.6

Words to symbols “What” becomes n “Is” becomes = Percent numbers become decimals “of” means multiplication

Example 90 is what percent of 20? 90 = p x 20 =4.5 * 100% = 450%

Solving % Problems by using Proportion A = RB Identify the Parts of the Percent Proportion The base, b, is always multiplied by the rate. In, 16% of 370, 370 is the base. The amount, a, is always by itself on one side of the equation. In “What percent of 18 is 4.5?”, 4.5 is the amount.

A, amount Base = b R= percent Rate A = b (R) When solving for percent, change decimal to percent

Set up Proportion Cross multiply and then divide By the variable’s coefficient Ex: Find 260 % of 40 Reduce fraction and cross multiply A(10)=40( 26) A = 104 A = 4 * 26

What percent of 4000 is 160? 400 p = 16* 100 4 %

END by Lori Tsutsui http://www.numberbasics.com