Chapter 5: Divide Decimals Standards: MAFS.5.NBT.1.2 ,MAFS.5.NBT.2.7

Vocabulary Words compatible numbers numbers that are easy to compute with mentally decimal a number with one or more digits to the right of the decimal point decimal point a symbol used to separate the ones place from the tenths place in decimal numbers dividend the number that is to be divided in a division problem division the process of sharing a number of items to find how many equal groups can be made or how many items will be in each equal group; the opposite operation of multiplication divisor the number that divides the dividend estimate a number that is close to an exact amount hundredth one of one hundred equal parts tenth one of ten equal parts

5.1: Division Patterns with Decimals Look for a pattern. Look for a pattern in these products and quotients. 560 x 1 = 560 560 x .01 = 5.60 560 x .001 = 0.560 560 x .0001 = 0.0560 560 ➗ 1 = 560 560 ➗ 10 = 56.0 560 ➗ 100 = 5.60 560 ➗ 1,000 = 0.560 560 ➗ 10⁰ = 560 560 ➗ 10ٰ¹ = 56.0 560 ➗ 10² = 5.60 560 ➗ 10³ = ___

5.1 Cont’d 225 ➗ 10⁰ = 225 ➗ 10ٰ¹ = 225 ➗ 10² = 225 ➗ 10³ = 2. 156 ➗ 1 = 156 ➗ 10 = 156 ➗ 100 = 156 ➗ 1,000 = 3. 86.3 ➗ 10⁰ = 86.3 ➗ 10ٰ¹ = 86.3 ➗ 10² = 86.3 ➗ 10³ =

5.3 Estimate Quotients You can use multiples and compatible numbers to estimate decimal quotients. Estimate. 249.7 ➗ 31 Step 1 Round the divisor. 31 rounded to the nearest 10 is _______ . Step 2 Round the dividend to a number that can be divided evenly by the divisor. 249.7 is between ______ and _______ . Step 3 Divide and solve. 240 ➗ 30 = ______ 270 ➗ 30 = So, two possible estimates are ______ and _____.

5.3 Cont’d Estimate the quotient. 338.7 ➗ 49 = _________ 2. 75.1 ➗ 9 = _________ 3. 96.5 ➗ 19 = _____

5.4 Division of Decimals by Whole Numbers Traditional/Old Fashion Method (i.e. the way your parents know how to solve these) 5 8.65 2. 3 2.52

Review What happens to the decimal point every time you divide by a power of 10? 67.8 ➗ 10⁰ = 67.8 ➗ 10ٰ¹ = 67.8 ➗ 10² = 3. Estimate the quotient. 89.6 ➗ 4 = 4. Divide. 161.2 ➗ 62= (Trailing Zero below) 5. 12.9 ➗ 0.6 =

5.6 Divide Decimals Step 1: Multiply both the dividend and the divisor by a power of 10 to make the divisor a whole number (or move the decimal over in the divisor… then the dividend). Step 2: Divide as you would whole numbers. Place the decimal point in the quotient, above the decimal point in the dividend. Ex: 3.4 4.42 Ex: 1.6 9.6 https://www.youtube.com/watch?v=Rdq6xIo8zIM&list=PLOJnQwI9yjLAedLjY5fPHqn--H86dRA59&index=48

5.6 Cont’d 0.3 0.24 45 ➗ 9 = ___ 4.5 ➗ ___ = 5 ______ ➗ 0.09 = 5

5.7 Zeroes in the Dividend (trailing zero) When there aren’t enough digits, you can add zeroes to the dividend (if you are getting remainders). Step 1: Divide as you would with whole numbers. Place the decimal point in the quotient above the decimal point in the dividend. Step 2: The difference is less than the divisor. Write a 0 in the dividend to the right of the last digit and continue to divide. Ex: 5.2 ➗ 8 = https://www.youtube.com/watch?v=LE55AHDazLc&list=PLOJnQwI9yjLAedLjY5fPHqn--H86dRA59&index=49

5.7 Cont’d 372 ➗ 15 = 2. 0.42 ➗ 0.35 = 3. 1.2 ➗ 9 =