6 CHAPTER R Review of Basic Concepts (c) 15 16 - 4 9 = 15 16 # 9 9 - 4 9 # 16 16 Because 16 and 9 have no common factors except 1, the LCD is 16 # 9 = 144. = 135 144 - 64 144 Write equivalent fractions with the common denominator. = 71 144 Subtract numerators. Keep the common denominator. (d) Method 1 4 1 2 - 1 3 4 = 9 2 - 7 4 Write each mixed number as an improper fraction. = 18 4 - 7 4 Find a common denominator. The LCD is 4. = 11 4 , or 2 3 4 Subtract. Write as a mixed number. Method 2 4 1 2 = 4 2 4 = 3 6 4 The LCD is 4. 4 2 4 = 3 + 1 + 2 4 = 3 + 4 4 + 2 4 = 3 6 4 -1 3 4 = -1 3 4 = -1 3 4 2 3 4 , or 11 4 The same answer results. S Now Try Exercises 55, 57, 71, and 75. Fractions are one way to represent parts of a whole. Another way is with a decimal fraction or decimal, a number written with a decimal point. 9.25, 14.001, 0.3 Decimal numbers See Figure 6. Each digit in a decimal number has a place value, as shown below. 4, 8 9 6, 3 2 8 millions ones or units tens hundreds thousands ten thousands hundred thousands 9 7 2 1 tenths hundredths ten-thousandths thousandths Whole number part Decimal point read “and” Fractional part • Each successive place value is ten times greater than the place value to its right and one-tenth as great as the place value to its left. Think: 9 2 # 2 2 = 18 4 3 parts of the whole 10 are shaded. As a fraction, 3 10 of the figure is shaded. As a decimal, 0.3 is shaded. Both of these numbers are read “three-tenths.” FIGURE 6
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