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Name: __________________Unit 2 Study Guide period: _______ Review of Decimal Multiplication and Division 13.45 x 32 142.5 x 0.13 81.4 x 2.3 12.45 ÷ 15 232 ÷ 0.75 423.5 ÷ 1.21 From Decimals to Fractions and Back: Strategies: Decimals to Fractions1. Read the decimal “like a mathematician.” 3.24 = “three and twenty four hundredths” 24 2. Write the fraction that matches! “three and twenty three hundredths” = 3 100 24 3. Simplify if necessary! 3 100 ÷ 44 = 3 256 Fractions to Decimals Sometimes works: ● Is it already in base ten? 1. Read the fraction like a mathematician. 2. Write the decimal that matches! 17 4 1000 = 4.017 Sometimes works: ● Can we make it base ten? 1. Create an equivalent fraction with the denominator that matches the decimal places (tenth, hundredth, etc). 2. Write the decimal that matches! 6 207 × 5 5= 35 6 100 = ALWAYS works: ● Fractions ARE division 1. Divide the numerator by the denominator! 3. Remember to add a decimal and annex 0’s! 4. Go out three decimal spaces. 2 7 6.35 = 2 ÷ 7 = 0.285 Practice: 41 100 6 50 = = 11 2 18 = 9 100 = 25 5 500 = 10 36 = 3 7 10 = 3 15 = 12 17 = Mixed Numbers into FG1 and Back: You can tell when you’re looking at a mixed number because _________________________________ _________________________________________________________________________________. You can tell when you’re looking at a fraction greater than one because ________________________ _________________________________________________________________________________. When you are converting between Mixed #s and FG1s, your goal is to create an equivalent fractional amount with “a different name.” → Just like I can be called Mrs. Hosek, Mrs. Hanna, or Sarah but I’m the same person, 3 13 , 103 , or 3 26 are all the same amount but just have different names. How we do it: FG1 to Mixed: Make them G.L.A.D. Mixed to FG1: Make them M.A.D. Multiply the denominator by the whole number Add that product to the numerator Denominator stays the same! Go divide! (numerator ÷ denominator) Leave whole number as t he whole number Always make the remainder the numerator Denominator stays the same! Practice: 11 2 18 = 95 36 12 17 = = 120 15 = Adding and Subtracting Fractions: 1. MUST HAVE common denominators! Show your work in the problem! 6 35 + 2 14 = 2. Simply if necessary! 6 35 × 44 + 2 14 × 55 12 5 6 20 + 2 20 = = 17 6 20 Subtracting Fractions with Regrouping: 1. MUST HAVE common denominators! Show your work in the problem! 6 15 + 2 34 = 6 15 × 44 + 2 34 × 55 = 4 15 6 20 + 2 20 2. Now you have two options: borrowing or converting them into FG1s. (Examples and practice on the next page!) Borrowing: 1. “Cross it out, make it less” 2. **Think about what “base system” your problem is in! --Add a denominator to your numerator** 3. Subtract numerators, denominators stay the same. 4. Simplify if necessary! Regrouping: Converting: 1. Make both fractions “M.A.D” 2. Subtract numerators, denominators stay the same. 3. Make your answer “G.L.A.D” 4. Simplify if necessary! Converting: Multiplying Fractions: Why it works: Multiplication is taking the first factor and replicating it the amount of times of the 2nd factor. → 4 x 3 is 4 three times, or 4 + 4 + 4 → 14 x 3 is 14 three times, or 14 + 14 + 14 (= 34 ) When the second factor is a fraction, it means the first factor is replicated less than one time. → 4 x 13 is 4 one-third of a time. You would find 13 of 4 by cutting 4 into three pieces and focusing on one of them. 4 x 13 = ________ → 14 x 23 is 14 two-thirds of a time. You would look at 23 of 14 by taking 14 , cutting it into thirds and focusing on 2 of them. 14 x 23 =________ ***You CANNOT multiply Mixed Numbers -- they MUST be changed into FG1s** How we do it: 1. You DO NOT need common denominators! 2. Convert to FG1s if necessary. 3. Multiply numerators to find your new numerator. 4. Multiply denominators to find your new denominator. 5. Simplify if necessary! 2 2 5x 33 2 11 5x 3 2 11 22 5x 3 = 2 11 22 5 x 3 = 15 22 7 15 = 1 15 Dividing Fractions: 1. The quick way to divide fractions is to “______, _______, _______.” 2. Once it is a multiplication problem, you can multiply like normal. ***You CANNOT divide Mixed Numbers -- they MUST be changed into FG1s FIRST** Practice of all operations: 11 7 15 - 3 15 = 3 2 12 + 3 5 = 11 2 15 x 3 15 = 3 2 12 x 3 5 = 1 6 x 45 = 2 15 ÷ 3 5 = 1 6 ÷ 11 15 ÷ 3= 12 16 - 3 45 = 4 5 = 1 23 + 1 49 = 3 x 1 49 = 3 ÷ 1 49 = Results and Reflection: Study Guide Reflection Section Score Reflection Need more practice? yes/no Decimal x and ÷ /6 From Decimals to Fractions and Back: Mixed Numbers into FG1 and Back: Adding and Subtracting Fractions Subtracting Fractions with Regrouping Multiplying Fractions yes/no /9 yes/no /6 yes/no /3 yes/no /1 yes/no /4 yes/no Dividing Fractions: /4 Name: __________________Unit 2 Study Guide period: _______ Review of Decimal Multiplication and Division 13.45 x 32 142.5 x 0.13 81.4 x 2.3 430.4 12.45 ÷ 15 18.525 232 ÷ 0.75 187.22 423.5 ÷ 1.21 _ 309.3 0.83 350 From Decimals to Fractions and Back: Strategies: Decimals to Fractions4. Read the decimal “like a mathematician.” 5. Write the fraction that matches! 6. Simplify if necessary! 3.24 = “three and twenty four hundredths” 24 “three and twenty three hundredths” = 3 100 24 3 100 ÷ 44 = 3 256 Fractions to Decimals Sometimes works: ● Is it already in base ten? 3. Read the fraction like a mathematician. 4. Write the decimal that matches! 17 4 1000 = 4.017 Sometimes works: ● Can we make it base ten? 5. Create an equivalent fraction with the denominator that matches the decimal places (tenth, hundredth, etc). 6. Write the decimal that matches! 6 207 × 5 5= 35 6 100 = ALWAYS works: ● Fractions ARE division 2. Divide the numerator by the denominator! 7. Remember to add a decimal and annex 0’s! 8. Go out three decimal spaces. 2 7 6.35 = 2 ÷ 7 = 0.285 Practice: 41 100 6 50 2 = 0.41 = 0.09 25 5 500 = 5.05 = 0.12 11 18 9 100 _ = 2.61 10 36 _ = 0.27 3 7 10 = 7.3 3 15 = 0.2 12 17 = 12.142 Mixed Numbers into FG1 and Back: You can tell when you’re looking at a mixed number because it is composed of a mix -- a whole number AND a fraction. You can tell when you’re looking at a fraction greater than one because _the numerator is greater than the denominator. The fraction has more parts in it than in one whole ( 12 7 has 12 parts but only needs 7 for a whole) . When you are converting between Mixed #s and FG1s, your goal is to create an equivalent fractional amount with “a different name.” → Just like I can be called Mrs. Hosek, Mrs. Hanna, or Sarah but I’m the same person, 3 13 , 103 , or 3 26 are all the same amount but just have different names. How we do it: FG1 to Mixed: Make them G.L.A.D. Mixed to FG1: Make them M.A.D. Multiply the denominator by the whole number Add that product to the numerator Denominator stays the same! Go divide! (numerator ÷ denominator) Leave whole number as t he whole number Always make the remainder the numerator Denominator stays the same! Practice: 11 2 18 = 47 18 95 36 23 = 2 36 12 17 = 84 7 120 15 = 8 Adding and Subtracting Fractions: 1. MUST HAVE common denominators! Show your work in the problem! 6 35 + 2 14 = 2. Simply if necessary! 6 35 × 44 + 2 14 × 55 12 5 6 20 + 2 20 = = 17 6 20 Subtracting Fractions with Regrouping: 1. MUST HAVE common denominators! Show your work in the problem! 6 15 + 2 34 = 6 15 × 44 + 2 34 × 55 = 4 15 6 20 + 2 20 2. Now you have two options: borrowing or converting them into FG1s. (Examples and practice on the next page!) Borrowing: 1. “Cross it out, make it less” 2. **Think about what “base system” your problem is in! --Add a denominator to your numerator** 3. Subtract numerators, denominators stay the same. 4. Simplify if necessary! Regrouping: Converting: 1. Make both fractions “M.A.D” 2. Subtract numerators, denominators stay the same. 3. Make your answer “G.L.A.D” 4. Simplify if necessary! Converting: Multiplying Fractions: Why it works: Multiplication is taking the first factor and replicating it the amount of times of the 2nd factor. → 4 x 3 is 4 three times, or 4 + 4 + 4 → 14 x 3 is 14 three times, or 14 + 14 + 14 (= 34 ) When the second factor is a fraction, it means the first factor is replicated less than one time. → 4 x 13 is 4 one-third of a time. You would find 13 of 4 by cutting 4 into three pieces and focusing on one of them. 4 x 13 = 14 x 13 = 43 = 1 13 → 14 x 23 is 14 two-thirds of a time. You would look at 23 of 14 by taking 14 , cutting it into thirds and focusing on 2 of them. 14 x 23 = 122 = 16 ***You CANNOT multiply Mixed Numbers -- they MUST be changed into FG1s** How we do it: 1. You DO NOT need common denominators! 2. Convert to FG1s if necessary. 3. Multiply numerators to find your new numerator. 4. Multiply denominators to find your new denominator. 5. Simplify if necessary! 2 2 5x 33 2 11 5x 3 2 11 22 5x 3 = 2 11 22 5 x 3 = 15 22 7 15 = 1 15 Dividing Fractions: 1. The quick way to divide fractions is to “keep, switch, flip.” 2. Once it is a multiplication problem, you can multiply like normal. ***You CANNOT divide Mixed Numbers -- they MUST be changed into FG1s FIRST** Practice of all operations: 11 7 15 - 3 15 = 3 2 12 + 3 5 12 16 - 3 45 = = 8 4 15 11 2 15 x 3 15 = 41 15 x 11 15 ÷ 3= 11 15 16 5 ÷ = 3 1 = 656 75 11 15 × 1 3 11 = 45 11 8 30 51 17 2 60 =2 20 3 2 12 x 56 = 8 75 1 23 + 1 49 = 27 12 3 5 3 5 x 3 5 11 5 3 5 ÷ 81 60 = 2 15 ÷ 1 6 = 3 x 1 49 = 21 = 1 60 = 1 4 30 7 20 1 6 = = x 45 = 11 15 × 10 = 1 45 5 3 55 = 45 = 1 29 ÷ 4 5 1 2 10 9 =3 9 = 2 15 3 1 x 13 9 = 39 9 = 4 39 = 4 13 3 ÷ 1 49 = = 1 6 × 5 4 5 = 24 3 1 ÷ 13 9 = 3 1 × 9 13 27 = 13 1 = 2 13