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Comparing Fractions To compare fractions, you need to make the two fractions have the same denominator. Step 1: Find the Lowest Common Multiple (LCM) of the denominators. Step 2: Change each denominator into the LCM of the two denominators. Step 3: Finally, whatever you did to the denominator to make it into the LCM, do the same to the numerator. Ex. 3 7 2 5 ↓ ↓ 15 35 14 35 Practice: 5 12 1 4 5 6 7 10 ↓ ↓ ↓ ↓ Comparing Decimals To compare decimals, you need to put the two numbers in the same place value. Step 1: Find the number that has the highest decimal value. Step 2: Change the other numbers so they are all in the same place value by adding zeroes to the end of the number. Ex. Tenths Hundredths Thousandths Hundredths Tenths 0.2 0.54 0.667 0.48 0.7 0.200 0.540 0.667 0.480 0.700 Thousandths Thousandths Thousandths Thousandths Thousandths ↓ ↓ ↓ ↓ ↓ Practice: Place each set of numbers in order from least to greatest. 0.65 0.113 0.92 0.037 0.47 Compare the two numbers. Write either > , < , or =. 0.87 0.724 0.34 0.391 Adding and Subtracting Fractions with Same Denominators Step 1: If the fractions have the same the denominators, you merely add or subtract the numerators, but keep the denominators the same. Ex. Subtracting Fractions with Same Denominators 7 12 6 7 - - 5 12 2 7 = = 2 12 4 7 = 1 6 Adding Fractions with Same Denominators 5 16 1 9 + + 3 16 4 9 = = 8 16 5 9 = 1 2 Note: If the answer can be simplified, then you must simplify it. Adding and Subtracting Fractions with Different Denominators Step 1: If the fractions have the different denominators, you must first make the denominators the same. Step 2: To make the denominators the same, find the Lowest Common Multiple (LCM) of the denominators. Step 3: Change each denominator into the LCM of the two denominators. Step 4: Finally, whatever you did to the denominator to make it into the LCM, do the same to the numerator. Step 5: Once the denominators are the same, you merely add or subtract the numerators, but keep the denominators. Ex. 1 2 + 1 3 ↓ ↓ 3 6 2 6 + 4 5 = = 5 6 - 1 2 ↓ ↓ 8 10 5 10 - = = 3 10 Changing Improper Fractions to Mixed Numbers Step 1: Divide the numerator by the denominator. Step 2: The answer is a whole number Step 3: If there is a remainder, place that back over the denominator and make into a fraction. Ex. 9 7 → 1 r2 7 )9 2 → 1 7 Practice: Change the improper fractions to mixed numbers 18 = 5 34 = 12 24 = 4 Changing Mixed Numbers to Improper Fractions Step 1: Multiple the whole number (the big number) and the denominator (bottom) of the fraction. Step 2: Add the answer from Step 1 to the numerator (top) of the fraction. Step 3: Place the answer from Step 2 over the denominator. Ex. Step 1 2 3 5 3 x 5 = 15 → Step 2 Step 3 15 + 2 = 17 17 5 → Practice: Change the improper fractions to mixed numbers 1 7 = 2 5 5 6 11 = 3 = 4 Improper Fractions An improper fraction is a fraction with a numerator that is greater than the denominator. Ex. 1 = 7 2 Ex. 2 = 22 11 = 8 4 Mixed Numbers A mixed number is a number written as a whole number and a fraction Ex. 1 = 3 1 2 Ex. 2 = 2 6 3 = 2 8 4 Multiplying Fractions Step 1: Multiply the numerators together, then multiply the denominators together. Ex. 6 7 3 8 X X 2 3 2 7 = = 6×2 7×7 = 12 49 3× 2 8×3 = 6 24 = 1 4 Note: If the answer can be simplified, then you must simplify it. Dividing Fractions Step 1: Take the second fraction in the equation and flip it, so that the numerator becomes the denominator, and the denominator becomes the numerator. The first fraction does not change. Step 2: Change the division sign to a multiplication sign. Step 3: Then multiple the two fractions. Ex. 1 3 5 6 ÷ ÷ 3 4 1 2 = = 1 2 X 3 1 5 4 X 6 3 = = 1× 2 3 ×1 5×4 6×3 = = 2 3 20 18 = Note: If the answer can be simplified, then you must simplify it. 1 1 9 Multiplying and Dividing Fractions and Whole Numbers 1. When multiplying or dividing fractions with whole numbers, convert the whole number into an improper fraction then multiply as you would normally multiply two fractions. 2. To convert a whole number into an improper number, make the whole number the numerator and 1 the denominator. Example: Multiplying fractions with whole numbers. 4 5 X 4 5 X 9= ↓ ↓ 9 = 1 36 1 =7 5 5 Example: Dividing fractions with whole numbers. 2 3 ÷ 5= 2 3 ÷ 2 3 X ↓ ↓ ↓ 5 = 1 ↓ 1 2 = 5 15 Multiplying and Dividing Mixed Numbers 1. When multiplying mixed numbers, convert the mixed numbers into improper fractions. 2. Then multiply as you normally would. Example: Multiplying with mixed numbers. 1 3 X 1 3 X ↓ 1 5 = 2 ↓ 11 11 5 =1 = 2 6 6 Example: Dividing fractions with whole numbers. 2 1 4 ÷ 9 2 ÷ 9 2 X ↓ 3 = 5 ↓ ↓ 3 = 5 ↓ 5 45 3 1 = =7 =7 3 6 6 2 ****Note: If you have to divide two mixed numbers, then you change both mixed numbers to improper fractions. Finding the Percentage of a Number 1. To find the percentage of a number, you only have to take the percentage and convert it into a decimal. To convert a percentage into a decimal, just move the decimal to places to the left. Remember all numbers have decimals. Examples: 82% .82 8% .08 233% 2.33 2. Once the percentage is converted to a decimal, multiply the decimal and the number you are trying to find the percentage of. Examples: What is 15% of 325? Step 1: 15% .15 Step 2: 325 x .15 = 48.75 Answer: 15% of 325 is 48.75 What is 6% of $67.00? Step 1: 6% .06 Step 2: 67.00 x .06 = 4.02 Answer: 6% of $67.00 is 4.02