Math Message Mark and label decimals on each number line below. 1..7. 2. 9.2 9. Writing Fractions and Decimals Write the numbers that your teacher dictates in the first column. Use the second column to show how you change these numbers to equivalent decimals. Write the decimal in the third column. Fraction or Mixed Number Calculations Equivalent Decimals 17
Renaming Fractions as Decimals 1. Fill in the missing numbers and shade the squares. Each large square is worth 1. Whole large square Shade 2 of the square. Shade 4 of the square. Shade 1 of the square. 2 a. 2 1. b. 4 1. c. 1. 2 1 Shade of the square. Shade of the square. 2 Write as a fraction and as a decimal. d. 2. e.. f.. 1 1 2. Write each number below as a decimal. Then use the letters to locate the decimals on the number line. 6 a. 1 2. b.. c. 4 1. d.. 1 e. 2 2 2 1. f. 2. g. 7. h. 1 1. 2 a.1.2..4..6.7..9 1. 1.1 1.2 1. 1.4 1. 1
Rounding Decimals Rounding removes extra digits from a number. Sometimes decimals are shown with more digits than are useful. Data with too many decimal places can be misleading. For example, measurements with too many digits might seem more precise than they actually are. Many calculators display results to eight or more decimal places. In most situations, one or two places are enough. The interest earned on a savings account at a bank is calculated to the nearest tenth of a cent. But the bank can t pay a fraction of a cent. Suppose one bank always rounds the interest down, and ignores any fraction of a cent. The First Community Bank calculates interest on one account as $17.21 (17 dollars and 21. cents). The bank ignores the. (or 1 ) cent. It pays $17.21 interest. 1. Here is the calculated monthly interest on Mica s First Community Bank savings account. Round each amount down to find the interest paid each month. January $21.4 February $22.4 March $1.29 April $19.24 May $17.427 June $1.916 How much total interest did the bank pay Mica for these 6 months? (Add the rounded amounts.) At the Olympic Games, each running event is timed to the nearest thousandth of a second. The timer rounds the time up to the next hundredth of a second (not the nearest hundredth). The rounded time becomes the official time. 11.47 seconds is rounded up to 11.44 seconds. 11.41 seconds is rounded up to 11.44 seconds. 11.4 seconds is reported as 11.4 seconds because 11.4 is equal to 11.4. Michael Johnson with his record-breaking time 19
Rounding Decimals continued 2. Find the official times for these runs. min: minute(s) s: second(s) Electric r Official Electric r Official 1.72 s. s 2.1 s. s 11.191 s. s 4. s. s 1.1 s. s 49.99 s. s 21.97 s. s 1 min.7 s min. s 2.92 s. s 1 min 9.991 s min s Supermarkets often show unit prices for items. This helps customers comparison shop. A unit price is found by dividing the price of an item (in cents, or dollars and cents) by the quantity of the item (often in ounces or pounds). When the quotient has more decimal places than are needed, it is rounded to the nearest tenth of a cent. 2.22 cents (per ounce) is rounded down to 2. cents. 24.769 cents is rounded up to 24. cents. 1.6 cents is halfway between 1.6 cents and 1.7 cents. It is rounded up to 1.7 cents.. Round these unit prices to the nearest tenth of a cent (per ounce). a. 2.74 b. 19.796 c. 29.27 d. 16.916 e. 2.641 f. 2. g. 1.469 h. 24.944 i. 17.21 j. 2.6 k. 21.66 l. 22.14 4. Describe a situation involving money when the result of a computation might always be rounded up. 14
Math Boxes 1. Write a 4-digit number that has in the hundredths place, in the tenths place, 6 in the thousandths place, and 2 in the ones place.. Write this number in words. 2. Rename each fraction as a mixed number or a whole number. a. 2 4 b. 6 6 c. 2 12 d. 4 6 e. 1 2 62. Write each mixed number as an improper fraction. a. 1 4 b. 1 2 4. Write the following numbers in order from least to greatest.. 4 7 4. 1 2 c. 2 7 d. 4 9,,,, e. 6 1. One week a family ate 1 boxes of 2 cereal. The next week they ate 1 4 boxes. How many boxes did they eat in the two weeks? 62 2 66 9 6. Wilkin School th graders wanted to donate boxes of canned food to their local food bank. They collected 1 boxes in days. How many more boxes do they need to collect? 7 71 141